In rereading my posts it looks like I'm trying to discourage you, which isn't the intent. I would like to shake you of the need to reach for a mileage number for the sake of hitting that mileage number, but it seems obvious you're trying to do that as a means to improving your running.
So I'll offer myself up as an illustrative example, highlighting some mistakes.
I'm 39, and prior to last year usually ran 30-40 mpw. The marathon buildup for that fall (2002) was the highest I'd done, in the 50-60 range. Earlier that year, I tried to jump from 35 mpw to 70 mpw and earned a month off with knee troubles. After the fall marathon (16 min PR), I hurt myself by starting up too hard and too quick, and spent the next two months struggling to get better.
Last year I built slowly from 50 mpw in January to hit 100 twice in mid-summer, with no real rhyme or reason to the way I was running the mileage. I was in the 50-70 range from mid-April to end May, and then eased up to hit 102 in mid-July and 100 again in August. The higher mileage made me faster at all distances from 5 k to HM, but I bonked (again) in the marathon and only shaved 6 s off the previous year on the same course.
This year's buildup is much more methodical. I built a good aerobic base from January to March, averaging 60-80, then eased back a little and shifted the focus to shorter interval work (1000s to 2000s) at 50-70 mpw combined with some races, and now I've shifted back to mostly aerobic work and higher mileage, with the intent of shaving some more minutes off a fall marathon. I've been to 93 mpw so far, but that was more by accident than design (well, not really so much by accident, as I did the sessions I had planned, but it was built around specific work sessions and daily running time, rather than mileage).
So far (knock on my wooden head) no injuries this year, and I'm confident I will shave a few more minutes, barring injury or lousy weather.
The points I'm trying to make are: reaching for a weekly mileage number for the sake of the number is more likely to lead to injury than desired results; and, the way you train in the weekly total is more important than the total itself.
Phew, I'd better get out for a run now. Good luck.