Nothing. Everything is either 2013 or 2017. Verry strang.
Discussion
You have no lightning address to zap.
Okay, the U.S. Bereau of Engraving and Printing says that although printing is down the past few years, it actually rose for most denominations from 2017 to 2019. This is definately strange. We should be seeing a more even distribution of dates. Can't wait to hear the theory.
https://www.bep.gov/currency/production-figures/annual-production-reports
Nice. I was wondering where to find that info. My Google skills suck. It looks like they print a lot of cash every year, but I feel like I'd see more variety in the printed date if that were the case.