3,173,491 Pinto's to be exact (according to Wikipedia). To put that in perspective there are 21,529,464 VW Beetles (the old one). So, there were about 7 times more VW Beetles produced than Pinto's. And, that being said how often do you see the older VW's these days? So, in terms of availability, yes, somewhat rare. In terms of total production, no.
Frankly back in 2007 when I went looking for a Pinto I was surprised that they weren't as plentiful as I recalled. It seemed like I had seem more around than there actually were. When I got my car people kept saying to me, "I haven't seen a Pinto in a LONG time." It was only then I realized that like anything that has aged, it becomes more scarce. Also, I see the numbers declining in the self serve yards I frequent. Again, going back to 2007 I was finding 1-3 Pinto with every trip. Recently it takes about 3 trips to find a single Pinto.