Popular Female Singers in the past 2 decades

Hi, can you name 10 most popular/favorite female singers (vocalist, artist) in the past 2 decades?

I want to collect the CDs for these singers and very often I heard those songs (mostly pop, movie theme sound track, etc) on radio FM103.5 or 107.9. But I don't remember or recognize their names or the songs.

Celine Dion and Britney Spears are just 2 examples. Thanks.