Mintages for recent years are usually unknown as auditing has not yet been completed, and the figures continue to change as they're calculated, and that's part of the reason why numismatic publications can't/don't have the information available for a couple years as they can't get it in advance, to include accurate numbers when the books co to be printed. There's a lot of information on the US Mint web site, Products & Sales Figures. Another source you can try, is reading the US Mint's Annual Reports. Also, sign up for email updates from Mint News Blog and/or Coin Update as they publish figures periodically from the same US Mint sources. For other countries, I don't have the same information.
