Atlanta ? The rate of newly reported HIV cases among blacks has been dropping by about 5 percent a year since 2001, the government said Thursday. But blacks are still eight times more likely than whites to be diagnosed with the AIDS virus.

The falling rate among blacks seems to be tied to overlapping drops in diagnoses among injection drug users and heterosexuals, Centers for Disease Control and Prevention researchers said.

The study was based on 2001-04 data from 33 states that have name-based reporting systems for HIV. Health officials do not know which diagnoses represent new infections and which ones were infections people had for years but had just discovered.

The CDC found that overall diagnoses in the 33 states decreased slightly, from 41,207 cases in 2001 to 38,685 in 2004. The rate fell from 22.8 cases per 100,000 people in 2001 to 20.7 per 100,000 in 2004.

The decline was more pronounced among blacks – the rate dropped from 88.7 per 100,000 in 2001 to 76.3 in 2004. Among whites, the rate rose slightly from 8.7 to 9.0.