While not XC, the reg for Iron Mountain Enduro tells the story:
U15 Boys:18
U19 Men: 22
19-29 Men: 4
30-39 Men: 8
40-49 Men: 19
50+ Men: 17
Pro Men: 4
Ebike open: 7
U15 Girls: 3
U19 Women: 2
AM Women: 7
Pro Women: 4
NICA likely feeding the U19 crowd and addressing the NICA HS slump of kids...