What is Siacoin's total supply?
Technically, an infinite supply of Siacoin will be generated. But the number of new coins introduced will slow as each new block is produced. At the beginning of 2018, there were just over 31 billion total Siacoin. By 2020, we should have about 45 billion tokens in circulation.
We also use a proof of burn mechanic which will lower the supply as hosts burn coins. You can find more info on this topic here.