According to her singles discography listing on wikipedia, before blackout, she only had 4 top ten hits (Baby one more time, Crazy, OIDIA, Toxic), only one of them being top 5 (Baby one more time). After OIDIA, it took 3 years for her next top ten hit, Toxic, which peaked at only 9. She then went 2 whole years without a hit.
Then Gimme More happened, and including that she has had 8 top ten hits (Gimme More, Circus, Womanizer, 3, Hold It Against Me, Till The World Ends, I Wanna Go, Scream and Shout), 6 of those being top 3, and 3 of them reaching the top of the chart.
Scream and Shout is also gaining on radio so expect to see her top 3 hits after blackout increasing to 7.