The 2007 numbers are from 34 states (and 5 areas) that require reporting. These are the highest infection rate states, but the total for 2007 was probably 63,000 rather than the 42,000 reported.

However, the ratios are probably the same.

half of new transmissions result from gay sex

a third result from straight sex

the rest are injection drug related

It seems in the US that the progression is as I thought in terms of behavior.

IV drug use-receptive anal intercourse–

Well, no. Not exactly.

I think you may be misreading the information. I provided numbers on exposure risk (the likelihood of any particular engagement with an HIV positive person leading to seroconversion).

If you wish to know the transmission rates in the US, here are the stats for 2007:

22,472 (53%) male to male

9,076 (21%) male to female

4,939 (12%) injection drugs

4,551 (11%) female to male

1,260 (3%) both MSM and drugs (exact unknown)

139 (0.3%) perinatal (mother to child)

59 (0.1%) other

IV drug use-receptive anal intercourse–

The surprise is the receptive vaginal intercourse (next), as I had imagined it was much lower (although still lower by a factor of 5 than the above).

Thanks for your effort Timothy…