Do peer reviewers receive any salary? Do academic peer reviewers receive any salary?
If yes, what is the annual average?
The vast majority not a cent, of whatever currency (see this answer for exceptions).

Peer reviewers are asked to volunteer, and they volunteer because they know that someone else would have to review their papers too (as Dilworth points out in a comment there can be other motivations too).

Said differently, peer reviewing is a mutual exchange, necessary for science to work (though the peer review system has been sometimes criticized).