What could have caused my daughter's drastic change in personality?

My daughter was always a really fussy irritable child, as she grew up she became very rebelious, she would do the opposite of everything I wanted. She was very popular at school and partied and had with guys and did drugs since she would always find ways to sneak out. It was very nerve racking and we would fight all the time because there was always something up with her, whether drugs, , shop lifting. She talked back all the time, would hit, yell, had the dirtiest mouth ever, and was always disrespectful....Then last year all of a sudden she one day just stopped doing this stuff and changed and began acting very very sweet and well mannered, being very respectful and angelic and telling me how much she loves me everyday, being very close to me, apologizing for everything and not doing anything wrong anymore. She's 17 now and has been doing very well in school for the past year and tells me she wants to become a surgeon. Why did her personality change so drastically? Is this common with a lot of teens?