You should want to know how many NBT are still in Blocks & Chains Exchange hands.
Those that have been paid for development or other costs add up to the 180,000.
It appears the NBT in circulation was rising after the buyback - former NSR holders who bought NBT with the BTC from the buyback?
The only thing you can know for sure is that the development funds of Nu and Blocks & Chains Exchange can be controlled more or less. All other NBT are in circulation or am I missing something?