The purpose of this post is to explore another interesting feature of our Hive blockchain - receiving interest on HBD. I would like share my understanding of how it works and present HBD interest payout data for the month of March 2021. All data is retrieved using HiveSQL which provides a separate table VOInterests with information like owner, interest and timestamp when interest was issued. I do not fully understand how exactly HBD interest payout works. I have more questions than answers on this topic. I hope those who have better knowledge can fill in the blanks.
Paying interest on HBD is one of Hive's unique features. Witnesses have an ability to change an APR parameter which would decide if interest is paid and at what APR. You can you check at hiveblocks.com, the APR column to see which witnesses using what value for this. It seems like current consensus is to issue 3% interest on HBD. This number might be slightly different based on how the actual APR is calculated. Does it take the average, majority value, or the median. For simplicity purposes let's go with 3%.
In this past all witnesses kept away using this parameter and for the most part the HBD interest rate has always been 0%. Witnesses decided to change this about a month ago. Here is how 
The goal is to encourage some additional holding of HBD, which will reduce the potential for HBD to drop below $1, in turn keeping the HBD stabilizer operating in a mode where it continually buys HIVE and sequesters it in the DAO. This, in effect, transmits demand from investors looking for yield (of which there is ample and widespread demand in the world today) into buy pressure for HIVE. This interest is sustainable, and indeed profitable for Hive stakeholders, to the extent that HIVE appreciates, over time, at a higher rate than the interest. To the extent that Hive is successful, this should be self-evident, and in some sense may also be self-fulfilling.
According to the data I retrieved using HiveSQL, it looks like first HBD interest payouts started on March 1st, 20021.
For the month or March total of 10429.131 HBD was paid out in 6486 transactions. Out of 6486 transactions payouts were made to 6415 unique accounts. For the most part in this month each receiving account got on interest payout. However, some accounts received two. I am not sure what that is. For example if you look at the chart below displaying top 100 interest recipients, you may notice 
Since the cases when one account received interest payout more than once were rare, I left the data as is without summing up the amount received for each account.
TOP 100 HBD Interest Payouts For March 2021
| # | Name | Amount | Date |
|---|---|---|---|
| 1 | upbitsteem | 3348.2540 | 2021-03-08 13:13:03 |
| 2 | hive.fund | 2895.7480 | 2021-03-13 19:31:42 |
| 3 | bittrex | 1232.9370 | 2021-03-12 19:23:48 |
| 4 | hot.dunamu | 341.7820 | 2021-03-16 03:58:09 |
| 5 | peak.fund | 265.3660 | 2021-03-18 17:30:39 |
| 6 | stan | 157.9700 | 2021-03-29 15:09:15 |
| 7 | phototutorials | 107.1490 | 2021-03-02 17:04:09 |
| 8 | springfield | 100.8190 | 2021-03-31 01:33:45 |
| 9 | altcoinpost | 100.1840 | 2021-03-02 16:59:09 |
| 10 | dlife | 81.8110 | 2021-03-02 17:08:39 |
| 11 | user.dunamu | 74.1150 | 2021-03-18 06:26:03 |
| 12 | peak.fund | 65.2690 | 2021-03-15 17:18:09 |
| 13 | gopax-deposit | 62.3060 | 2021-03-09 22:20:39 |
| 14 | teamsmooth-mm | 56.9920 | 2021-03-26 18:26:24 |
| 15 | steemengineteam | 53.5650 | 2021-03-18 21:03:39 |
| 16 | jasonclay | 53.2750 | 2021-03-30 01:58:36 |
| 17 | aldentan | 46.6670 | 2021-03-30 05:12:03 |
| 18 | initial.bid | 46.0190 | 2021-03-22 20:45:00 |
| 19 | peak.proposals | 39.9260 | 2021-03-04 20:29:48 |
| 20 | dsongs | 37.1430 | 2021-03-02 17:12:39 |
| 21 | preferansist | 30.5240 | 2021-03-22 20:45:00 |
| 22 | kylealex | 25.8430 | 2021-03-27 16:29:18 |
| 23 | dapeng | 20.0280 | 2021-03-29 11:53:30 |
| 24 | silentobserver | 18.8770 | 2021-03-22 22:31:27 |
| 25 | innuendo | 18.4790 | 2021-03-20 09:42:12 |
| 26 | soulturtle | 16.9380 | 2021-03-14 16:48:24 |
| 27 | polonius79 | 16.5310 | 2021-03-10 16:34:30 |
| 28 | promote.helper | 16.0600 | 2021-03-06 00:52:12 |
| 29 | askaran | 14.0420 | 2021-03-20 21:05:24 |
| 30 | applemint | 13.5890 | 2021-03-22 08:05:30 |
| 31 | coinlend | 12.9090 | 2021-03-30 08:32:03 |
| 32 | beanz | 12.3700 | 2021-03-18 12:02:09 |
| 33 | auctionator | 12.3110 | 2021-03-22 21:11:48 |
| 34 | blocktrades | 11.5110 | 2021-03-11 23:25:12 |
| 35 | anarchyhasnogods | 11.1080 | 2021-03-30 03:59:39 |
| 36 | ionomycold | 10.4260 | 2021-03-03 18:30:18 |
| 37 | fiftysats | 10.3370 | 2021-03-08 20:11:36 |
| 38 | handmade | 10.3340 | 2021-03-28 21:29:03 |
| 39 | moar007 | 9.9500 | 2021-03-28 15:34:36 |
| 40 | ettydiallova | 9.8020 | 2021-03-30 11:47:27 |
| 41 | gooddream | 9.4530 | 2021-03-16 03:41:06 |
| 42 | mariostucablog | 8.6660 | 2021-03-12 00:41:12 |
| 43 | crypto-guru | 8.6330 | 2021-03-23 23:35:03 |
| 44 | shimul.khan | 8.6090 | 2021-03-31 15:50:27 |
| 45 | omrusman | 8.4880 | 2021-03-30 10:33:18 |
| 46 | epictoken | 8.2020 | 2021-03-31 07:04:42 |
| 47 | ecency | 7.5680 | 2021-03-16 09:29:51 |
| 48 | yellocat | 7.5510 | 2021-03-28 02:25:51 |
| 49 | steemitpresident | 7.3200 | 2021-03-09 12:34:21 |
| 50 | discernente | 7.2070 | 2021-03-05 11:25:00 |
| 51 | bemypet | 7.1980 | 2021-03-22 08:20:36 |
| 52 | karunya | 6.9760 | 2021-03-15 06:19:21 |
| 53 | yoonteacher | 6.8560 | 2021-03-07 09:10:18 |
| 54 | qustodian | 6.8090 | 2021-03-22 19:54:18 |
| 55 | steembasicincome | 6.6620 | 2021-03-28 16:26:45 |
| 56 | ahka | 6.2980 | 2021-03-20 09:39:42 |
| 57 | svuvya | 6.2640 | 2021-03-24 10:38:24 |
| 58 | internutter | 5.9040 | 2021-03-19 23:42:12 |
| 59 | pinheiroemmanuel | 5.7900 | 2021-03-10 16:48:15 |
| 60 | peterchung | 5.7550 | 2021-03-24 06:39:39 |
| 61 | beckymeep | 5.7460 | 2021-03-15 01:32:00 |
| 62 | markup | 5.5950 | 2021-03-29 06:51:33 |
| 63 | jose-poveda | 5.5780 | 2021-03-14 21:29:09 |
| 64 | orukpeyendis | 5.2240 | 2021-03-08 10:16:27 |
| 65 | dgiver | 5.2230 | 2021-03-02 16:25:51 |
| 66 | jarvie | 5.1690 | 2021-03-04 23:25:03 |
| 67 | dragonslayer109 | 5.0730 | 2021-03-26 19:27:54 |
| 68 | jringo | 5.0530 | 2021-03-23 12:35:24 |
| 69 | tunjex12 | 5.0520 | 2021-03-20 12:48:06 |
| 70 | zvezda51 | 5.0420 | 2021-03-24 10:31:12 |
| 71 | triablot | 5.0160 | 2021-03-06 14:49:48 |
| 72 | fullalt.dhf | 4.9270 | 2021-03-02 10:29:48 |
| 73 | nathansifugaming | 4.8500 | 2021-03-04 03:18:39 |
| 74 | itsallasong | 4.7780 | 2021-03-18 21:32:00 |
| 75 | poetrybyjeremy | 4.7570 | 2021-03-13 20:58:18 |
| 76 | pakhar | 4.6680 | 2021-03-14 21:28:57 |
| 77 | michaelwrites | 4.5680 | 2021-03-23 21:55:00 |
| 78 | keychain | 4.5530 | 2021-03-25 08:29:51 |
| 79 | hadialhendi | 4.5350 | 2021-03-29 09:33:00 |
| 80 | upbot43 | 4.4960 | 2021-03-31 12:17:48 |
| 81 | tombstone | 4.4610 | 2021-03-20 22:26:30 |
| 82 | gopaxkr | 4.3830 | 2021-03-15 10:14:36 |
| 83 | steemh | 4.3440 | 2021-03-29 06:34:42 |
| 84 | bahtiarlangsa | 4.0170 | 2021-03-18 15:37:30 |
| 85 | andysupriady | 4.0100 | 2021-03-29 09:24:18 |
| 86 | yuemay | 3.9840 | 2021-03-22 08:06:27 |
| 87 | graphenelab | 3.9090 | 2021-03-18 14:05:06 |
| 88 | oflyhigh | 3.7390 | 2021-03-06 14:00:03 |
| 89 | zainenn | 3.6800 | 2021-03-07 20:58:48 |
| 90 | royalfinest | 3.6470 | 2021-03-30 22:18:21 |
| 91 | kingsiste | 3.6320 | 2021-03-24 20:01:27 |
| 92 | tonac | 3.5480 | 2021-03-03 22:38:00 |
| 93 | ppita | 3.5030 | 2021-03-29 19:54:18 |
| 94 | cee | 3.4980 | 2021-03-21 16:31:30 |
| 95 | swarddraws | 3.4670 | 2021-03-15 05:23:18 |
| 96 | rubelynmacion | 3.4620 | 2021-03-30 23:38:24 |
| 97 | app | 3.4130 | 2021-03-19 15:26:30 |
| 98 | coruscate | 3.3020 | 2021-03-05 02:03:54 |
| 99 | nightwolf | 3.2840 | 2021-03-31 22:28:45 |
| 100 | neoxian | 3.1730 | 2021-03-13 05:13:12 |
As I already mentioned about total of 6415 unique accounts received total of 10429.131 HBD as interest payout. Many of these unique accounts received under 1 HBD. So, if we exclude those accounts, we can see that 231 accounts received total of 100020.877 HBD
Similarly if we only count those who got 5 HBD and more then we will have 71 unique accounts receiving total of 9673.246 HBD.
If we only count those who got 10 HBD and more then we will have 38 accounts receiving total of 9449.514 HBD
In other words about 90% of total HBD interest payments are going to 38 accounts. But we also need to consider that this only the first month. In my understanding, the purpose of this action is to encourage more users to have HBD on their own accounts rather than in exchanges.
So if you look closely, you will see the top recipients of the HBD interest are the exchanges and the DHF. This raises another question. Do the users who deposited HBD in exchanges get any benefits of the interests paid out. Probably not. It would probably be not worth putting in the effort to distribute the interests to the users in the exchanges, since usually funds in the exchanges get traded and moved a lot. So far, I haven't seen any exchange announcements on this topic.
Moreover, those users who send HBD to exchanges probably wouldn't care much about 3% interests either. Those who care have an option to keep their HBD in their own accounts.
This brings up another interesting idea. The other day I saw 
Last thing to mention on this topic is that it seems to me interest payouts were not sent to those who have HBD in Savings. I manually checked a few accounts and didn't see any transaction related to this. There is only total of 51,185 HBD in Savings. While it may not be a big issue, I think HBD in Savings should be able to receive interest as well.
If you are curious who has how much HBD in liquid or savings balance, you can visit https://hivelibrarian.herokuapp.com and use the Rich List section. You can filter the results by HBD, HBD-Savings, or other assets.
If you know the answers to any of the questions expressed above please let me know. If you see that made some mistakes, feel free to correct me. Let me know your thoughts in the comments. Thanks.
Update: Make sure to read Smooth's comment below that adds more clarification.