Patrick,
If you are comparing top level golfers and the distance disparity, I think the differences are probably equal percentage wise.
I recall Deane Beaman and a few others were short hitters at about 240 when Nicklaus was hitting it 300+. Now that is 260 and maybe 325 (yeah a few 350+ drives each year, but then JN hit a few 325 or so) Both are about 25% differences.
Now, if you are comparing the average guys, still stuck at 225 and the top guys, yeah. Or seniors often still stuck at 190-200 (think it was closer to 180 years ago) then the difference has multiplied a lot.