This stats is quite interesting. Moreover, I would like to suggest some additional data/analysis about the percentage of “sent postcard” per “requested address postcard” for each country/territory. It reflects the performance of postal service in each countries/territory.
e.g. Country A has 100 requested postcards, but 90 postcards reach their destinations. That means 90% of postcards reach the destination. (More percentage means more efficiency for postal service in each country/territory.)
Although some “requested” postcards are not sent, but it should be assumed that all of requested postcards are sent via postal services.
I hope you will consider this suggestion for the next year stats or it will be better if you make this additional analysis for 2022 and present the additional result to Postcrossers.