Just to clarify, it’s actually roughly ~3% of the reward during the Founders’ Reward (e.g. the first ~4 years), and the amount of pledged ZEC is slightly less; the total amount the Foundation will receive is roughly ~260,000 ZEC.
These are not “official” numbers, but happy to share the current state of our ZEC holdings all the same: we’ve spent ~25,000 ZEC, and thus have around 235,000 ZEC remaining in pledged ZEC. We plan on publishing a more thorough “state of finances” early next year.