In general, cars at the high-turnover self-service junkyards tend to be 15 to 20 years old, but some types of cars disappeared from junkyards long before their time. The Pinto was such a car.
Believe it or not, the Pinto was once as common on American streets as, say, the Sentra is today. The rep for exploding in rear-end collisions was relatively undeserved (plenty of Detroit cars with the gas tank mounted between the rear axle and the bumper had explosion problems), but Ford didn't win itself many friends with those memos showing that Dearborn's bean counters preferred to pay wrongful-death settlements than redesign the car.
The last Pinto was sold in 1980, and by 1990 you hardly saw them in junkyards; only the wretched first-gen Hyundai Excel passed through the junkyard phase of its lifecycle more quickly. That's why it's a memorable occasion when I find a Pinto in the junkyard these days; someone kept this thing running- or at least stored- for decades after most of them had long since been rendered into cubes of China-bound scrap steel.