How does the AlgoExplorer find the circulating supply?

I started running a node a couple days ago and couldn’t figure out how to reproduce the value shown on the AlgoExplorer for the circulating supply. The fields I could see on my end were onlineMoney and totalMoney, and while onlineMoney matched the staking amount shown on the explorer, totalMoney was only slightly more than half the circulating supply number reported on the explorer.

I tried summing onlineMoney and totalMoney and while that was closer it was still off by over 73m Algo.

Am I missing something on my end or is there actually not a way to reproduce this number easily?