Days between report level date range filter
I'm trying to calculate MinutesUtilized as a percentage of minutes available on a custom date range. I already have a metric MinutesSpent which is a total of the minutes spent per period. I already have a report level filter which the user can select the date range of interest. I know that I have a fixed 500 minutes available per day, so what I want to do is:
MinutesUtilized = (MinutesSpent)/(500*NumberOfDaysInDateRange)
Where I'm stuck is: How do I get the NumberOfDaysInDateRange pulled out of a report level date filter?