The following is the result of a Pearson correlation performed using SPSS.
The data on Muslim population proportion are from here; the data on FGM prevalence are from here.
Download the data set here.
Caveats: I am almost certainly not qualified to analyze these data appropriately. (I have a semester of behavioral health stats under my belt, but I do not use the information regularly.) In some cases, Wikipedia lists a range of FGM prevalence. I tried to use the figure that appeared to be most reliable.
Is this a significant correlation? According to this reference, a value between .40 and .69 is considered a “strong relationship.” So, .504 would be considered a significant correlation.