HIV-1 subtype distribution in the AMC. A. Numbers of HIV-1 non-B subtypes detected in patients visiting the AMC (Amsterdam, the Netherlands) from 1996-2012. “Unknown” consists of circulating recombinant forms (CRFs) other than CRF01_AE and CRF02_AG as well as difficult to type, complex mosaic strains and possible new subtypes. B. Percentages of HIV-1 B and non-B subtypes in the patient population according to the transmission risk group of HIV-1 that could be retrieved from the database. The total number of sequences (N) analysed in each group is indicated.