Here is the site that I used while TTC and now that I am Pg. It's about hormone levels. If you go down to the bottom you will see the section on progesterone levels in pregnancy.
http://www.fertilityplus.org/faq/hormonelevels.html
Chart:
Progesterone in Pregnancy
1st Tri - 10-90 ng/ml
2nd Tri - 25-90 ng/ml
3rd Tri - 49-423 ng/ml
Average is about 20 at 4 weeks LMP, and 40 at 14 weeks LMP. It is important to note that while a higher progesterone level corresponds with higher pregnancy success rates, one cannot fully predict outcome based on progesterone levels. Progesterone supplementation is unlikely to help if started after a positive pregnancy test.