The "past 15 years" would not include the current year (2013). For the 15 years
of 1998-2012, the Atlantic Coast Conference (ACC) had 12 Final Four teams, as did the Big Ten-- except that NCAA infractions forced Ohio State to vacate its 1999 appearance, which would make the Big Ten's count 11. The Big East had ten teams during this timeframe.
Over the "last 15 years," which is what you might mean, the Big Ten has had 13 teams (including the vacated Ohio State appearance); the Big East 12; and the ACC 11. The "last 15 years" would be 1999-2013, but your use of "past" is the more correct term of art. By definition, the "last 15 years" would suggest that the event had come to an end and that here would be no more,
which is not expected to be the case.
big ten
the pac-10
This makes 14!!
The answer to that easy question is SEC, Big TEN, TIED BABY (DICK VITALE, LOL)
either Roy Williams or Dean Smith
UCLA with 10, Cincinnati and Duke with 5
Including the 2012 NCAA Tournament: Brigham Young University has made the Tournament 28 times and has never made it to the Final Four. Missouri is second, with 26 appearances without ever making the Final Four. Xavier, which so far has won in the 2012 tournament as this is being written, is third with 22 years without an appearance.
http://www.mibazaar.com/ncaa/ has the last 70 final scores games, with teams and location
Brigham Young University has made 22 NCAA Tournament appearances without advancing to the final four. This is as of the end of the 2007 season.
Eleven teams have played in consecutive Final Fours in the NCAA. UCLA has the record with 10 appearances from 1967 to 1976.
Through 2013, Butler University has made appearances 12 years in the NCAA men's basketball tournament.
As of 2009, 22 NCAA tournament appearances. 3 elite 8 appearances prior to the 2009 tournament.