How many requests an actual number, not a percent. To get the number from the percentage, assume you've got p% observations (which is 97.5%). The actual number of observations is p*900/100, that is 9 times the 97.5% or 877.5 observations (I know, odd thing you get a non-integer). I guess I got the wrong percentage (I don't do statistics just yet at school ;) )
