How about just the last five years, then?
Perked rides with their considrable higher K/Ds are far off the right. They all have comparatively little usage.
With both charts, only A2A kills & deaths did count.
As said before, that ENY is not just about plain usage or air to air success, but also raw performance aspects and most importantly, multirole capability.
ENY values also fulfill two functions in the arena, one determining the perks gained in combat and second as a limiter for balance purposes (which sometimes leads to odd results, giving you much more perks for shooting down a rather helpless Lancaster than a B-17).