The Stellar network allows users to vote on who will earn its 1% annual STR inflation. I am wondering - is this information publicly available on the Stellar ledger or somewhere else? How can one find out which account voted for who and how big their voting power was at the time of the vote?
Yes, the information is public and in the ledger history.
you can find how inflation works in Stellar.org's mandate https://www.stellar.org/about/mandate/#Stellar_creation and https://www.stellar.org/developers/learn/concepts/inflation.html
in a nutshell: you can look at the inflation transaction that runs every week and look at its metadata. The metadata will tell you who was the recipient of the inflation.
As far as re-computing the input, you need to:
- Download the historical ledger this inflation transaction ran against (so the one right before it)
- (can be skipped to get a fairly close approximation) apply the transactions that precede inflation during that ledger round (can be done with the metadata or running a node)
- Look at the balance and InfladionDest of all accounts in the ledger to compute the vote tally. Voting power is the STR balance in the account.