You can also try ethnicity/religion/beliefs as your cross cultural component. For example, Bar/Bat Mitzvah is performed once a Jewish adolescent reaches a certain age. I can't remember off the top of my head but it may have been 16.
I think you should also try and define "freedom". What I mean by this is: to what extent do you consider it to be "freedom"? For example, when an Australian adolescent reaches 18, going by law and legal stuff, is this the age which you think "freedom" starts?
You can compare different culture/religious beliefs (eg. Islam, Judaism, Christianity, Hinduism, Buddhism etc. etc.) within the Australian adolescent community and see which culture/religion allows the earliest/latest freedom and at which stage, during adolescence, they perform a rite-of-passage. You can also blend 'gender' within this, as S39 mentioned above.