I agree with what Charlie Brumbaugh said and will not repeat it, but will offer an perspective on what the individual can do.
The single most effective thing you can do to improve your acclimatization rate is to get in good aerobic shape before starting your trip.
Ability to acclimatize varies enormously among individuals, and, for an individual, ability to acclimatize can depend on the altitude. Some people are fine at modest elevations (say, 14,000 feet and lower) and then just top out.
Ability to acclimatize will eventually lessen with age, but at what age the decline becomes noticeable will again vary enormously with the individual. And, again, staying aerobically fit will postpone that decline. Moreover, if you take several yearly trips, you may find your ease of acclimatization actually increases with the years (for awhile.)
As for weather, naturally you will be able to move more briskly if it is not too hot, but this would be true at sea level. As long as you are pushing yourself but not exhausting yourself -- and staying hydrated -- you will acclimatize.
Statistics won't tell you anything about yourself at altitude or anywhere else.