Please Help with Percentage Calculation for a Report Formula

Hey community! Hoping someone can help me craft what must be a simple custom formula in a summary report that I just can't figure out. 

In my screenshot, I have a simple summary, and what I'm trying to do is calculate the percentage of "confirmed" and have it as a live percentage. I need to divide the confirmed count into the sum of all the dispositions. 

I figured out the (Contains([Cashflow],"confirmed")), thinking this may be part of the formula but when I try to get the sum it seems not to take things like "+" or "OR" when trying to sum all of the dispositions. 

So need a Report Formula that does this:

[Cashflow],"confirmed" / Sum of ("confirmed","empty","maybe","declined","pending")
or 
[Cashflow],"confirmed" / Total of [Cashflow]

for each month, or row

doable? 

THANK YOU!
Bobby 



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Bobby Hollis
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