I search through pennies at work and I also coin roll hunt, and I find a lot of 1980s. I see a lot more of them than I do the years surrounding 1980. I thought it might be because a lot more pennies were minted in 1980, but here are the mintages from 1977 to 1983, if my math is correct: 1977: 8,667,243,452 1978: 9,841,966,181 1979: 10,161,549,429 1980: 12,558,358,466 1981: 12,869,048,760 1982: 16,729,361,847 1983: 14,222,833,554 There were more pennies minted from 1981-1983 than there were in 1980. Why is it that I see so many?
I think a lot of our observations will depend on where we are located. Although I have seen a lot of 1980 pennies, I can't say that I have seen more of those than I have '81 through '84. The distribution seems pretty even to me. What I have noticed lately (in my neck of the woods) are 1994 pennies in high grade. I suspect the Federal Reserve (or some large bank) had them stashed and recently released them. It is possible that it is a coincidence, but I have literally seen dozens of them recently and all in high grade which leads me to believe it isn't a coincidence. As for quarters, I see a lot 1965. No surprise given the high mintage for that year. I also see a lot of 1995 and 1996. On the more uncommon side... over the last week I have gotten a 2009 dime and 1973S cent in my change.
Would be interesting to do a study (ie, keep a count of all the dates you see in rolls), but probably not worth the time and effort. I wonder also if the 1980 are more durable and the older zinc cents just haven't made it through the last 30 years as well.
I once told a friend of mine about pre-1965 quarters and how they are mostly silver. I knew I broke a cardinal CRH rule in telling, but he is a good friend and would probably give up after a week anyway. So he calls me like 3 times during that first week to tell me "Oh I got so close! I got another 1965!". At first I didn't explain it to him since he seemed excited, but after that 3rd time I said, "Dude, you're nowhere near close. Just cause it's one year from the last silver year doesn't mean you're close. That is one of the most common years". Haha
While looking at all those common 1980 cents and 1965 quarters you might want to keep an eye open for the nice doubled dies that can be found on both.
I've been saving all pocket change for years. I can tell you that over the past five years you can expect to get about 20% copper cents versus zinc cents. It is changing by the year to the zinc side. I'm guessing that it will be 15% by 2020 and probably move to 5% by 2025.
I think your estimations are a little high. When I was searching penny boxes I was getting about 13% coppers.
I'm in central New York and it is kind of a depressed area. It might be a little higher in copper cents here. I will also agree toyz that it runs in cycles. I get more some months than others.