The thing about teenagers is that the thrill and convenience of driving often takes precedence over the bicycle, which is "old news," as most kids have known how to ride a bike well before age 16. Cars for many teenagers are still equated with freedom, not "cages."
No offense taken--I may have been overly defensive. And I suppose having lived in only in Portland, I'm ill-qualified to make any statements about the relative number of Cyclists in this city. I would assume, however, that it's somewhere between the per-capita numbers of Topeka and Amsterdam.
EDIT: I haven't gotten my liscense yet.