This heavily heavily depends on the population you choose, given the difference in sexual habits.
As a data point, the paper below shows 1,213 out of 18,401 high-risk people in France got infected in 4 years (and 260 out of 31,992 with the previous gen prep, it seems this one reduces it by ~10x again)
https://www.thelancet.com/journals/lanpub/article/PIIS2468-2...