During this period, there were changes to the U.S. Mint annual Proof Sets in terms of which coins were included in the sets, mostly in terms of the quarters included. 2020 was the tenth year of the America the Beautiful series, and the last year that five different quarters were issued. That year a special bonus coin was also included in the Proof Set that spurred higher sales of the 2020 set.
In 2021 only two quarters were in the set—the final America the Beautiful Quarter and the one-year only Washington Crossing the Delaware Quarter. The sets still sold well that year likely because so many collectors like the one-year only quarter.
Then in 2022, a new quarter series for American Women debuted, which meant the inclusion of five quarters from the first year of that series in the 2022 sets.