At 16 everyone is different, everyone is a study of one? Age shouldn't be a determinant or benchmark of where you should be at, that's what practice is for? The way we practice, should be more of a determinant. When I was 16, I had just finished with a year of all-state band and was putting in an hour of day of practice with 2 hours of playing had the acceptable double/triple tonguing playable range up to high D, and was playing music like Haydn, Hummel, Artunian trumpet concertos. Everyone is different; that same year I met a very accomplished trumpet player who was applying to Juilliard.