so I have taken your figures and added a little. Below is the SBD and VEST payments claimed on the 1st March. Using http://www.steemdollar.com I have converted these values to STEEM.

Based on this, the available STEEM is 72% of payment claims accepted. A lot higher than I expected
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I did a report too and got a value very similar to your first chart above where you have 64% available I have 62% for organic votes.