As a % it happens extremely rarely however just this weekend talking to non racing people the perception is starting to be the exact opposite, that it happens a lot. The people I was talking to who know what I do brought up the topic saying they had seen 'yet another' report of fighting at the races and then went on to say how there is no chance they would take their young family racing anymore as it is just full of young lads getting pissed up.
Racing needs to be very careful with its perceived reputation into the future.