The scanning method is explained here.
|Region||Realms||Guilds scanned||Characters scanned|
I was somewhat surprised to see Europe coming out ahead of the US, but the heavily populated Russian realms probably made the difference. This doesn't reflect active subs of course - many subscribers have multiple 85s and many subscribers have none at all.
By the number of scanned players.
|Taiwan||死亡之翼 (Deathwing)||9,546||血之谷 (Bleeding Hollow)||28,155|
|Korea||블랙무어 (Blackmoore)||294||듀로탄 (Durotan)||13,520|
The difference between the low and high population servers is pretty extreme - 27 times in the US and 46 times in Korea. This is partially explained by the smaller realms being pretty new.
Based on the number of scanned players (active 85s).
|US||Némesis (Nemesis)||Ðream Ðivinity||916|
|Europe||Shattered Hand||D A W N||941|
|Taiwan||銀翼要塞 (Silverwing Hold)||偽娘黑澀會||912|
It's hard to imagine what being in a guild of almost a thousand active 85s is like. Probably pretty different. That's 3 times the size of the whole active population on some realms.
Guilds with the most achievers.
|Europe||Ревущий фьорд (Howling Fjord)||Синестезия||22|
|Korea||라그나로스 (Ragnaros)||La Invictus||6|
Guildmates often work on the achievement together, so seeing 2 or 3 from the same guild is fairly common. The Russains are pretty hardcore though - 37% more Insane than the number 2 guild.
Based on when the achievement was completed.
|Before it was added||107|
|Wrath of the Lich King||10,930|
You can see a big spike at the end of WotLK, due to an announcement by Blizzard that the achievement would be taken away. Players rushed to finish an epic achievement and earn the title. Cataclysm came out with the achievement still in place, but with relaxed requirements (no more Shen'dralar rep needed) and so the rate of earning stayed high while players who were almost done finished it up. The big spike at the end of the graph (Jan/Feb 2012) was due to patch 4.3.0 making Darkmoon Faire rep much much easier to obtain.
The relationship between active population and insanity.
There's a pretty strong relationship between active realm population and number of insane achievers. There are few outliers, like Ревущий фьорд (Howling Fjord) with 155 out of 15,939 insane (high) or 亞雷戈斯 (Arygos) with 21 out of 21,090 (low). The full data is available in this google doc.