I thought it would be nice to have an updated list with all the #1 singles by pop girls in every relevant market so this is what I have so far. This only includes acts who made their commercial debut in the past 20 years. Non-official and radio charts aren't counted. I might be missing some girls so feel free to post them!
Australia:
Rihanna (8)
P!nk (7)
Britney Spears (5)
Katy Perry (3)
Shakira (3)
Christina Aguilera (3)
Lady Gaga (3)
Kesha (3)
Taylor Swift (2)
Gwen Stefani (2)
Avril Lavigne (2)
Beyoncé (1)
Adele (1)
Kelly Clarkson (1)
Austria:
Rihanna (5)
Britney Spears (4)
P!nk (3)
Shakira (3)
Katy Perry (3)
Lady Gaga (3)
Christina Aguilera (2)
Kesha (1)
Avril Lavigne (1)
Belgium:
Shakira (9)
Britney Spears (8)
Rihanna (6)
Adele (6)
Katy Perry (4)
Lady Gaga (4)
P!nk (2)
Christina Aguilera (2)
Beyoncé (2)
Lorde (2)
Kesha (1)
Kelly Clarkson (1)
Canada:
Rihanna (11)
Katy Perry (10)
Britney Spears (9)
Christina Aguilera (5)
Shakira (4)
Lady Gaga (4)
Taylor Swift (3)
Kesha (2)
P!nk (2)
Kelly Clarkson (2)
Miley Cyrus (1)
Avril Lavigne (1)
Adele (1)
Carrie Underwood (1)
Lorde (1)
Denmark:
Britney Spears (4)
Rihanna (4)
Lady Gaga (3)
Katy Perry (2)
Shakira (2)
Beyoncé (2)
Christina Aguilera (1)
Finland:
Britney Spears (5)
Lady Gaga (4)
Rihanna (3)
Shakira (2)
Adele (2)
Katy Perry (1)
Christina Aguilera (1)
P!nk (1)
France:
Shakira (5)
Rihanna (5)
Britney Spears (3)
Lady Gaga (2)
Christina Aguilera (1)
P!nk (1)
Beyoncé (1)
Adele (1)
Germany:
Rihanna (5)
Shakira (4)
Lady Gaga (4)
Britney Spears (3)
P!nk (3)
Katy Perry (2)
Adele (2)
Kesha (2)
Christina Aguilera (1)
Beyoncé (1)
P!nk (1)
Ireland:
Britney Spears (7)
Rihanna (5)
Lady Gaga (5)
Katy Perry (4)
Christina Aguilera (4)
Beyoncé (4)
Shakira (4)
P!nk (2)
Kesha (2)
Adele (2)
Kelly Clarkson (1)
Avril Lavigne (1)
Lorde (1)
Italy:
Shakira (5)
Britney Spears (4)
Rihanna (2)
Adele (2)
Katy Perry (1)
Beyoncé (1)
P!nk (1)
Avril Lavigne (1)
Kesha (1)
Lady Gaga (1)
Lorde (1)
Japan:
Lady Gaga (1)
Britney Spears (1)
Netherlands:
Britney Spears (4)
Shakira (4)
Lady Gaga (3)
Katy Perry (3)
Beyoncé (2)
Avril Lavigne (2)
Rihanna (1)
Christina Aguilera (1)
P!nk (1)
Adele (1)
Kesha (1)
Kelly Clarkson (1)
New Zealand:
Katy Perry (9)
Rihanna (5)
Britney Spears (5)
Christina Aguilera (5)
P!nk (5)
Beyoncé (4)
Shakira (3)
Fergie (2)
Avril Lavigne (2)
Lady Gaga (2)
Brandy (2)
Taylor Swift (2)
Miley Cyrus (1)
Kesha (1)
Adele (1)
Gwen Stefani (1)
Lorde (2)
Norway:
Britney Spears (6)
Rihanna (6)
Christina Aguilera (3)
Lady Gaga (3)
Beyoncé (3)
Katy Perry (2)
Kesha (2)
Shakira (1)
Adele (1)
Avril Lavigne (1)
P!nk (1)
Spain:
Shakira (8)
Lady Gaga (5)
Britney Spears (3)
Miley Cyrus (1)
Christina Aguilera (1)
Beyoncé (1)
Rihanna (1)
P!nk (1)
Avril Lavigne (1)
Adele (1)
Sweden:
Britney Spears (4)
Rihanna (3)
Lady Gaga (3)
Christina Aguilera (2)
Shakira (2)
Katy Perry (1)
Kesha (1)
Beyoncé (1)
Avril Lavigne (1)
Switzerland:
Rihanna (8)
Shakira (5)
Britney Spears (4)
Adele (3)
Christina Aguilera (2)
Katy Perry (2)
Lady Gaga (2)
Beyoncé (2)
P!nk (1)
Kelly Clarkson (1)
United Kingdom:
Rihanna (8)
Britney Spears (6)
Beyoncé (5)
Katy Perry (4)
Lady Gaga (4)
Christina Aguilera (4)
Kesha (3)
Miley Cyrus (2)
P!nk (2)
Shakira (2)
Avril Lavigne (1)
Adele (1)
Lorde (1)
United States:
Rihanna (13)
Katy Perry (9)
Britney Spears (5)
Beyoncé (5)
Christina Aguilera (5)
Kesha (4)
P!nk (4)
Kelly Clarkson (3)
Fergie (3)
Adele (3)
Lady Gaga (3)
Taylor Swift (2)
Brandy (2)
Gwen Stefani (1)
Miley Cyrus (1)
Shakira (1)
Carrie Underwood (1)
Avril Lavigne (1)
Lorde (1)
Total #1 singles:
Rihanna: 99
Britney Spears: 90
Shakira: 67
Lady Gaga: 61
Katy Perry: 60
Christina Aguilera: 43
P!nk: 37
Beyoncé: 35
Adele: 28
Kesha: 24
Avril Lavigne: 17
Kelly Clarkson: 10
Lorde: 9
Taylor Swift: 8
Miley Cyrus: 6
Brandy: 6
Fergie: 5
Carrie Underwood: 2
Sources: Billboard, OfficialCharts, ChartsInFrance, FIMI, ARIA, etc.