At age 15, I am sure the number of boys infected with HIV through having sex with men is zero, or very, very close to zero.
It will rise steadily with age.
If 5.6% is the average for ages 15 to 44, it will be about 11% at age 44, and still rising except that the median age of death is about 40.

So where does 1.6% come from?
Can you post a source?
Did you make it up for your own purposes?
Please explain, because it appears to be another attempt to deceive.