I doubt you'll find them, because I don't think the studies were done on fitness across a wide spectrum of the population.
My family came from farm and hillbilly stock, and 10 pushups for my grandparents in their '60s? Not something they'd consider doing or something they'd consider any great feat. It varied heavily even then depending on lifestyles. They were active, but never exercised. Exercise didn't become a thing until the sedentary desk culture became dominant. It only got worse with the introduction of the computer.
"Fitness" as something adults did past a certain age really didn't hit until the '70s and '80s. Jane Fonda and leg warmers. Rec team leagues for adults and the (somewhat) acceptance of soccer in the US. Gyms that had more than free weights.
Let's look at obesity percentages between the '80s and now. Obviously diet has played a huge role, but lifestyle (activity) certainly has changed. Objects in motion tend to stay in motion, and the amount of energy it takes to get a larger object moving is correspondingly greater. Take a look at how kids spend their time after school now vs then. Heck, take a look at your old yearbook and then compare body types at that same school today.
How's SCNCA's road license numbers this year as compared to the last ten years?