I found this chart on Americanpregnancy.org. Seems like hcg levels can vary widely.
Guideline to hCG levels during pregnancy:
hCG levels in weeks from LMP (gestational age)* :
3 weeks LMP: 5 50 mIU/ml
4 weeks LMP: 5 426 mIU/ml
5 weeks LMP: 18 7,340 mIU/ml
6 weeks LMP: 1,080 56,500 mIU/ml
7 8 weeks LMP: 7, 650 229,000 mIU/ml
9 12 weeks LMP: 25,700 288,000 mIU/ml
13 16 weeks LMP: 13,300 254,000 mIU/ml
17 24 weeks LMP: 4,060 165,400 mIU/ml
25 40 weeks LMP: 3,640 117,000 mIU/ml
Non-pregnant females: <5.0 mIU/ml
Postmenopausal females: <9.5 mIU/ml