Try this, took about 30 seconds to write and test, I got 11 taps per second ... hope the code is right ;)
taps = 0 mostTaps = 1 clock = MilliSecs() Repeat If KeyHit( 57 ) Then taps = taps + 1 If MilliSecs() - clock >= 1000 If taps > mostTaps Then mostTaps = taps taps = 0 clock = MilliSecs() EndIf Cls Text( 0, 0, mostTaps ) Text( 0, 20, taps ) Until KeyDown(1)