this is incomplet.

annual interest rate of steem : 9.5% !

But the created steem are seperated allocated !
75% of the created Steem for Reward Fund !
15% of the created Steem for Steem Power Holder
(10% of the created Steem to the Witnesses)

you get 15% of 9.5% inflation for your vested steem

which is 1.425% annual interest rate for steem power Holdings !

(source: @steemitblog
https://steemit.com/steem/@steemitblog/proposed-changes-to-steem-economy)