Since our apps moved to the Dev Dashboard, the app Overview shows Earnings, Install events and Uninstall events, plus the current Installs count. The old Partner Dashboard also had Merchant growth, the cumulative number of active stores with the app installed over the selected range.
Is that metric planned for the Dev Dashboard, possibly as part of the upcoming App history view?
Our workaround for anyone else who needs it: query app events through the Partner API, treat installed/reactivated as +1 and uninstalled/deactivated as -1, and keep a daily running total. It works, but a native chart would be much easier.