Current month vs 4 month average delta

[#1]

Hello,

I am using the following expression in my chart to return a percentage for a specific method used. I am doing this over the course of 4 months (month1,month2,month3)

=num(Count({<MethodDesc={'1'},UtilizationMonthName={'Month0'}>} Distinct Key) /count({<MethodDesc={'2','3', '4'},UtilizationMonthName={'Month0'} >} distinct Key),'#,##0%')

I am not sure how to go by getting the average of this percentage though over the 4 months. Any help would be great.

Thank you.