The two most recent Majors have been the least predictable. Diamond coins used to be fairly achievable, but the coins for Rio and Paris both seem to have required a good dose of luck.
We looked at public Steam inventories to find the rarity of these coins. We looked for the Paris Major data in May 2023, and found 4k total coins to create this distribution. Data for the other five Majors in the graphic was pulled in December 2022 (40k inventories searched, 21k coins found in total).
Where are the Bronze Coins?
You may have noticed that there is no info on Bronze coins in this post. If you lock in your picks for each stage, that will get you to the Silver coin (even if you don't get a single pick correct). So since this analysis is focused on how difficult it is to get Diamond at the most recent Majors, we have omitted information on Bronze coins.
For Berlin, you also had to complete some in-game challenges alongside getting the correct picks (thanks u/iamambience). This makes data for that Major fairly inconclusive, as you could have gotten lots of picks correct, but been held back by not completing the in-game challenges.
Sample sizes for each Major in the graphic:
Paris: 4100 coins found
Rio: 7600 coins found
Antwerp: 5100 coins found
Stockholm: 4600 coins found
Berlin: 1900 coins found
Kato: 2000 coins found
After finding around 5000 Rio coins, pulling more coins did not significantly change the fraction of Diamond coins, so we decided that we had reached a representative sample. However, we found fewer coins as you travel further back in time, so the uncertainty rises on the older Majors. This disparity is potentially due to CSGO's popularity rising, or due to more people doing Pick'Ems for recent Majors.