12%

I only have 3 of the 25 Albums That Should Not Have Been Recorded - feel free to guess which three as I'm not telling. (found via John H)

And unsurprisingly, an album described as:

A concept album about a shape shifting toy that looks like a cross between an armadillo and a tank that battles a half scorpion/half lion toy for the fate of planet Earth

was made in the 1970s.