No1 - Madonna's album sales havn't been "steadily declining" the past decade...

"Music" (11m), "American Life" (4m), "Confessions... " (10m) ", "Hard Candy " (4m)

No2 - "Even with Gaga sales" Last time i checked "BTW" had SOLD (not shipped) 5.5m copies and if you take away the 500k 99 cents sales that's 5m, Just 1m more than "Hard Candy".