How well is STEEM Power protected from inflation...really?

So I've been observing my "stash" of Steem Power the past few days and noticed that while the "virtual_supply" has been increasing on average around ~1.37% per day, my Steem Power holdings have increased around maybe 1.31% each day. While this at first may seem to not be a huge difference, when extrapolated out over a year the difference becomes a whopping 21.9%. Which basically means our SP has lost 21.9% in market cap "value" in the span of just one year (unless I'm mistaken, which is entirely possible heh).

So my questions are...what forms of inflation is our Steem Power not protected against? Can we expect the increases in virtual supply as compared to SP to continue as they are, or will this difference shrink over time?

Any and all input is greatly appreciated.

Thanks, and STEEM on!!