I calculated the probability of the S&P500 having a down month, can you tell me what caused the difference in the two probabilities?

Also, for X I set it as 0% for a down month, is it correct or do I need to change it?

I Period 1 Mean Stan.Dev. 0.67% 4.67% 0.00% -14.45% 44.25% Period 2 0.19% 7.79% 0.00% -2.40% 49.04% Prob. I Period 1 Mean Stan.Dev. 0.67% 4.67% 0.00% -14.45% 44.25% Period 2 0.19% 7.79% 0.00% -2.40% 49.04% Prob