why retractable needles won't have a large impact

This from the following site:

http://www.health.qld.gov.au/sexhealth/clinical/HIV_AIDS.shtml

"Who was diagnosed with HIV infection during 2000?

The average age was 35 years for males and 30 years for females

89 per cent were male

11 per cent were female

homosexual male contact accounted for 61 per cent of exposures, injecting drug use for four per cent, and heterosexual contact for 23 percent."

and

"there may be as few as 5,000 infectious virus particle per ml of blood compared with hepatitis B in which there may be as many as one billion infectious virus particles per ml."

Hence Hep B is far and away more transmissible than HIV