“I asked for parishes that made the switch to all male altar servers what their server numbers were like before the switch and what the number of servers was about a year after the switch.
“That’s hard to argue with. The average parish surveyed, when switching from co-ed servers to male-only, saw their server numbers grow 450%.”
https://www.cal-catholic.com/parishes-that-switch-to-altar-boys/
St. Stephen the First Martyr (FSSP) in Sacramento, CA, has 110 altar boys.