IMO, if we were going to find a correlation, it might be more about each person's formative years in shooting that might show us something, if anything.doesn't look like there is a huge correlation between age and caliber
As I only shoot my own handloads, I find the economical advantage to 9mm far more than slight. Because I do not cast, bullets are (by far) my largest expense and 9mm allows me to use very nearly HALF the bullet weight. That doesn't save me half the cost (of even the bullet) but it is significant.9MM & 45ACP for range use with a slight advantage to 9MM for economy with factory ammo.
I can't say I'm surprised at the results here because:
.45 ACP and I'm 22.