http://www.gay.com/hivplus/study-intermittient-condom-use-nearly-as-useless-as-no-condom

Highlights:

Only one in six gay men were able to avoid HIV infection with inconsistent condom use for anal sex over a four-year period.

If used consistently and properly, condoms still boasts high effectiveness rate. According to NBC News, condoms cut risk of HIV infection by about 80%; essentially, a less than a 1% chance of infection per year.