SkipE99

Just to help you out a little more. I would pick a standard dev of around 2%, with a mean of 1.2%. Recall that 67% of results are within 1 std dev of mean, 96-ish% are within 2. From your limited results above, I think you want 3% and -1% within the first deviation band, and probably <5% outside of 4% from mean.

Your excel formula is then: =NORMINV(rand(),0.012,0.02) for your simulation.