How to create new data table with Measures as values

Hi All, 

I have raw data as below:

table 1 customer list throughout the years uploaded daily

 table 2 customers who left and dates

table 3 customer who joined and dates

Please note that all data is for past 3 years with thousands of customer IDs and with relationship to a date table. 

Then, I created a measures table with measures for:
Customer Leave (COUNTA(table 2[date])
Customer Join (COUNTA(table 3[date])
Average Customers (AVERAGEX(VALUES(table 1[date]), CALCULATE(COUNTA(table 1[customer ID])))

Currently, I'm displaying the measures as line/bar charts with dates as x-axis.

How can I create a new data table (not just visual) with columns Month, Year, calculated Join Count, calculated Leave Count, and calculated Average Customers? This is because I want to do forecasting on the columns down the road. 

Something like this (random numbers)

Thank you!