After logging into DocuSign as an administrator, the reports are available. These can be found as a menu item at the top between the "Templates" and the "Settings".
When you open the reports, you can select the type "Envelope" on the left side of the page. There you will find the report type "Report on envelope volume". After opening this report, you can select the desired period and receive a result about the actual use and how many envelopes have already been signed.