I was surprised with Lady Gaga's results with her second album. its not normal to decline like that on your 2nd album, when your 1st one was a "Phenomenon".
Madonna found her peak with "Like a virgin" and she maintained the succes with the next album.
Like a virgin 21M
True Blue 23M
Britney the same with "BOMT" and "Oops"
Baby one more time 25M
Oops I did it again 20M