Insanity Fit Test Day 1 to Day 15

So i didn't think that i would improve any, but I am happy with my results.

Those that have done this, is this a normal improvement?

Switch Kicks - 38 to 41
Power Jacks - 33 to 36
Power Knees - 50 to 60
Power Jumps - 14 to 25
Globe Jumps - 6 to 10
Suicide Jumps - 6 to 8
Push-up Jacks - 10 to 14
Low Plank Oblique - 17 to 30