Made a century

I scored over a hundred yesterday in bowling. I have tried many a time to cross it starting from 17 and reaching 99 couple of times. I try to throw the ball straight at the pins knocking none , few , some , all - at different times. Some amount of spin and the ball goes straight into the gutter.  But the balls keep getting heavier after the first game.  

Coming to the other bowling (cricket) , i can only throw not bowl !!