In this chart, the globalness of an artist is measured by how many countries the artist has gone #1 on iTunes. (both songs and albums are accounted for)
rank) Artist (country)
1) Beyoncé (113)
1) Taylor (113)
3) Nicki Minaj (110)
4) Katy Perry (107)
5) Sia (106)
6) Adele (104)
7) Ariana (102)
8) Rihanna (97)
9) Selena G (94)
10) Lorde (90)