How can I calculate the percentage of shipments that are edited by my members?

You can manually calculate the percentage of club shipments that have been edited. 

Navigate to Clubs > Packages > select the package > go to Step 3: Members

Next, use the filter tool and select Build = Edited 

This will give you the number of club shipments that have been edited and you can divide by the number of total club shipments to get the percentage. 

Alternatively, you can explore the option of create a customer report through the Custom Reports app built by Treefrog Digital. 

For more information and contact; https://commerce7.treefrogdigital.com/customreports/