Really confused about steem power.

Hello there fellow steemians!

So I've read through dozens of articles now about the topic but I've still not come across anyone clearly explain the two sets of numbers I have in steem power.

607.968 STEEM
(+27.552 STEEM)

Its the number in brackets which confuses me. I made a deposit onto my account to try and increase the steem power. So the top number - 607.968 rose. However the number in brackets rose only by a few decimal points.

Would anyone be able to explain these numbers to me a little better?

Thanks a bunch!