You beat me to to it, I could not remember where I'd read it but knew statistically the odds were low. ?
However, It's also interesting to pose the same question though about our defending and why teams appear to have greater success against us?
One thing I've noticed from all of the training footage on RTV or the photo galleries is we never seem to be seen practicing defending set pieces or defending high through balls. Even in the mini games our defenders are defending against our style but that's not what happens in the real games. I'm sure we must doing it, but it does beg the question, when we seem not to be improving in this area.