>>2015199thats fair. but now look at the amount of land that was developed into suburban sprawl at the same time. The preservation of land while simultaneously developing land rapidly is a great example of the "nature can go elsewhere" paradigm. basically: "its ok to develop here because we aren't developing there.". additionally, land was much cheaper back then especially remote land, so acquisition for protection was cheaper. The only stats that would mean anything would be a comparative set of data that compares the real value expended on acreage for development vs for protection over the decades to see what the change has been. that would actually be a very interesting to see.
I think its also important to consider the how of development. for example the municipal standards for development used to have very limited considerations for habitat protection in that generation, now it is much more significant in a lot of localities, with development restrictions on critical areas and special considerations for landscaping that provides habbitat or naturalization, and the advent of reclamation projects.. thats much harder to quantify though.
