Here's the endurance page in the wiki.
http://www.carnageblender.com/wiki/Endurance
Also a copy and paste from the endurance page showing the effectiveness of endurance.
A Few Data points
6.5 mil named ToE - .515 (51.5%) Endurance.
5.8 mil named ToE - 0.505 (50.5%) Endurance.
3.6m ToE - .49 (49%) Endurance.
3 mil level ToE - .45 (45%) Endurance.
1.1 mil level ToE - .41 (41%) Endurance.