That's crazy, unless the count of houses has increased tremendously since the 80's (it may have).
Seeing a distribution would help. Also seeing the definitions.
Then I've also seen a house double in size when you add heat to a basement and proper egress. Lots of houses built in the 50's/60's can double legal size this way, without altering the footprint. You can get 3000 sq ft on a typical suburban 1/3 acre lot doing this.
Thanks for the links, now I'll be down the rabbit hole in excel!
Yea, I've seen a LOT of properties bought for the full price just to raze it and build new.
Interesting stuff.