You can get this through table calculations. The only thing that you need to set is how it should be computed. Look at the screenshots below.
1. Once you place the SUM(Total), right click on it and do a quick table calculation. Then edit the table calculation and proceed to step 2.
2. Compute as given below. If you click the "Show calculation assistance", it would highlight as shown below to indicate how the value would be computed.
A 2018.1 workbook is attached. Hope this helps.
Month over Month Growth.twbx 66.0 KB