1-15 Believers = up to 150DE
15-20 Believers = 150-200DE
20-30 Believers = 250-300DE
30-40 Believers = 350-400DE
40-50 Believers = 450-500DE
50-60 Believers = 550-600DE
60-70 Believers = 650-700DE
70-80 Believers = 750-800DE
80-90 Believers = 850-900DE
At least that's what logic would dictate to me, but don't quote me on that, I've not got that far yet (I'm rubbish at these games - no patience, and I've lost about 6 tribes now because I go away and leave it on 'fast'!)