You've got me curious now. I never tested it in high school, but I could dunk pretty easily from a standstill and hurdled a 66" high jump bar, but I had really good hurdling technique and flexibility, which probably mattered a lot more than jumping ability. I jumped onto a roughly 60" concrete wall at a local park for fun a few times last winter, but then stopped that kind of training when I slipped and split open both shins to the bone. But again, I think that's more flexibility than jumping ability. I know I can't dunk any more.
Anyway, I might test it over the weekend now. You notice with basketball players that the transition to the 30s is when they seem to lose their explosive jumping ability. I turned 29 a few days ago. It would be interesting to see if I could ever get it back. I never touched a weight in high school. All I did was run.