Use the Membership Counts Year over Year report to view total member counts year over year.
How to use it
Navigate to Reporting > Membership and click on the "Visualize Member Counts" report
On the following page, you will see a graph showing overall membership counts on a monthly basis over a year.
You also have the options at the top left of the toolbar to add additional years for comparison, and the ability to filter by specific Member Types to compare trends at that level