Well the ratio of finding silvers vs clad was certainly higher in the 70s and early 80s.Silver coins are nice, I have found out over the past 50 years or so they are becoming harder and harder to find, out here when I do find one they are deteriorated to scrap value. So for me I prefer parks, where I can find jewelry, or prospecting where I find nuggets. If I add up the scrap value of silver coins found over the past 10 years, I might get $50, but the scrap value of jewelry might be $5k, (I'm off but just a ratio)
Parks vs cellar holes is another factor.
But usually when they show up it's a good day of digging.