Your graph shows real numbers, NOT transmission rates. Although the annual numbers for both (hetero and homo) are about the same, this means that rates of transmission are massively higher for MSM than for heterosexuals.
Rates of infection amongst MSM have increased dramatically in the last decade. Approx 25% of all new infections, to approx 70% at the end of 2011
HPA also say that when all the figures for 2011 are available, the real numbers will be in the order of 3000 new cases.....appox the same rise in MSM infection rates as previous years.