My 02 Beezer had 27,500 on it when I sold it. It was 9 months old at the time and I only had it for 5 of them; it was a demo before that. 10,000 per year might be what is considered average but that it dragged down by people who don't use (or even need) their cars. My 306 has done 20k since February as I now do much less mileage but that is still 36k/year.
I'm not convinced I see the point of buying a diesel for under 20k or even 25k a year.