That would be either integer or decimal, but the choice would really depend on how you intend do do the calculations using those numbers.
Do you want to do them as 150 x 0.75 to represent 75%, or do you want to do them as 150 x (75/100) to represent 75%.
The former is more comvenient for calculations, but less convenient for displaying (since most people want 75 and not 0.75 for display purposes). The latter is the opposite.
So, you pick which version, and choose a columne type that is suitable.
-- gw (www.railsdev.ws)