The Y axis shows actual cases of syphilis. That top "MSM" red line is entirely the product of the small percentage of men who are homosexuals/bisexuals.
Homosexuals have 6 times more syphilis infections? OMG! Probably 6 times total STDs. I guess the Gaystapo have taken control of the group that is looking into antibiotic resistance. Since they’ve figured out how to stop transmission of HIV, homosexuals figured they could have all the sex they desired. My guess is that HIV is going to turn out more problematic than homosexuals thought.
Another thought: why is just women listed? Why not WSM?