Cu pennies are becoming more and more scarce with each year that passes. It's not just the zinc dilution effect either. More people have gotten hip and are culling copper pennies from circulation. I'm afraid the good old days of pulling 20-30% Cu pennies from bank boxes are over.
I started culling Cu pennies from circulation in the late 80's. Before the Ryedale came out, it was all manual hand sorting -ugh. I could never do that now. I'm quite happy with what I've accomplished and my current Cu stash.