Well, it is not a race many high school guys run on the track. According to milesplit stats for last year, 13 guys in the nation were sub 15 in track, and 2 of them were from California -
For cross country, it looks like 23 guys did it last fall, 3 of them from Calif.
It is not very common in any state.
You would think it would be more common than it is (15:00 track 5k ~ 9:15-9:20 3200m), but with so few 5k's run in HS track, and cross country courses naturally slower than a track, it isn't all that common. 100's of kids out there capable, just not many that are actually doing it.
DyeStat's lists have this many going under for the last couple years:
2011 Cross: 19
2011 Track: 13
2010 Cross: 23
2010 Track: 14
2009 Cross: 25