Well, the percentage is a way of saying: You do not encounter a compiler bug in day-to-day-programming. 'four compiler bugs in 12 years' is just another way of

Well, the percentage is a way of saying: You do not encounter a compiler bug in day-to-day-programming. 'four compiler bugs in 12 years' is just another way of saying: You do not encounter a compiler bug in day-to-day-programming. (Note the 'day-to-day'. Day-to-day-programming and 'all programming you do in x*10 years of C-programming' are very different sets of code written)