Excel errors (#VALUE!) on Monte Carlo report graph when returns are bad

@wmchbaker This is the result of a test scenario never envisioned in the PRC design and which is not handled gracefully by the code: your modeling period is only four(4) years in duration and the column where you're seeing the errors presents the success rate for the last 10 years of the modeling period. The six years where you're seeing the #VALUE errors are the six years prior to the modeling period. This "error" will likely never be fixed.

Stuart