P-1 factoring, relative primes

[timbit]

Hello,

First time post, using Prime95 for a long time.

Quick question regarding P-1 factoring and the number of relative primes for Stage 2. I apologize in advance if this has already been answered but I could not find and answer in previous posts.

I recently completed Stage 2 P-1 work on a number in the low 80M range. The number of total relative primes was 960 (as opposed to the 480 I normally see for numbers in the 45M-55M range). I had my memory set at 1600MB. B1=920000, B2=29670000.

I am just starting Stage 2 P-1 work on a number in the high 99M range. The total number of relative primes is 480. My memory is set at 1600MB. B1=1110000, B2=35242500.

What determines the total number of relative primes during the Stage 2 P-1? What is the mathematical reason for this? I thought bigger numbers means more relative primes, but that's not always the case?

Thanks.