http://www.ssa.gov/cgi-bin/babyname.cgi
It was #15 in the States in '07, but that was actually slightly down from '06. I'll be curious to see where it is in '08. One problem is, though, that people have been spelling it
Mya sometimes (I think-- I am never quite sure when it is spelled
Mya whether it is pronounced as
Mia or
Maya!)