Hmmm… how was it, how many Postcrossers there are in Finland? And how many cards have been sent form here during 15 years of Postcrossing? How much does it cost to send a postcard? You can now find this information from a little sticker you can put on a postcard and share info to the world. BTW our ranking by sent postcards is 5th, which means that we are probably the most active country in the world when the population is taken into account!
Statistics are from www.postcrossing.com (August 2020) and will be updated now and then.
Size of the sheet is 9,5 cm x 12,5 cm and there are 10 stickers on it (sticker size is 2,6 cm x 4,3 cm).