Pennies were copper until 1982, I think and the metal content got changed in other coins. People are hoarding copper.
Bad link
Pennies changed from 95% copper & 5% zinc in mid-’82. Those are worth about $0.03 each right now - but they’re illegal to melt down. It is now 97.5% zinc...and, surprisingly, its melt value is very slightly above $0.01. So the government loses money on every cent that they produce (and, of course, you have to add in mintage and shipping costs).
No other coin’s composition has changed since then. I can understand why nickels aren’t there - its melt value is about $0.07, and was close to $0.09 last week when nickel spiked (they’re also illegal to melt). But ALL nickels (except the War Nickels) have had the same composition for over a century, so why those from the 70s and 80s would be missing I don’t know, other than that so many new ones have been made. War nickels are worth close to $1.40.
Dimes, quarters and halves have a melt value of about 30% of their face value.
More details here: https://www.coinflation.com/coins/basemetal_coin_calculator.html
Silver coin melt value calculator: https://www.coinflation.com/coins/silver_coin_calculator.html
Dime and quarter composition has remained the same since ‘65...nickels longer than that. 75% or more copper, the rest nickel. A lot of people are separating out copper cents, myself included.
I wouldn’t draw too many conclusions from one stash of coins. What were the factors determining what you put into it? Are you finding lots of nickels from the ‘50s snd ‘60s? I go through rolls looking for things, and I can make some generalizations based on what I’ve seen, but it’s a pretty small window into what the big picture might be.
Pennies are zinc now.
Deadly to dogs.
I hate them and usually don’t even accept pennies in change unless they’re copper.