there have only ever been 18 perfect games in baseball history.
18 perfect games. since 1875 there has been 263 no-hitters.
In the New York Mets Franchise History, there have been 33 one-hitters, 1 no-hitters (June 1, 2012) and 0 perfect games
As of now (April 23, 2012) there have been 21 perfect games thrown. Most recently was April 21, 2012 by Philip Humber of the Chicago White Sox against the Seattle Mariners.
Only one perfect game has been thrown in the postseason, done by Don Larsen in 1956 postseason against the Brooklyn Dodgers. There have been only two no-hitters tossed on playoff history, with one of them being Don Larsen's perfect game. The other was by Roy Halladay (the 2010 postseason against the Cincinnati Reds).
1 Don Larsen 1956