I can't edit my post because I don't know why, but here's the quote:
Even among pro users, notebooks are by far the most popular Macs. In second place are iMacs. The Mac Pro is third. Apple declined to describe the Mac Pro’s share of all Macs sales any more specifically than “a single-digit percent”, but my gut feeling is that the single digit is a lot closer to 1 than it is to 9.