Puberty in asian girls?

do you guys think that asian girls start puberty later than white/black girls? on average? i started puberty when i was around 15-16yrs old and i heard the average for "girls" is 9 - 13? I feel like i'm like 2-3 years behind. lol. well anyway, does anyone know on average how long puberty lasts? i'm 20, going on 21 in a few months and i still have acne!! & i grew lke.. half an inch within the last six months. Thanks:).