Within the reporting area you can select other campaigns to compare against the current campaign.
The Compare performance function is located above the Conversion Funnel
When clicked, the Compare campaign performance window opens.
Use the check boxes to select the campaigns you wish to compare and click on the COMPARE button.
The campaign(s) you selected are compared against the current campaign and all the statistics such as opens, clicks, etc are shown.
Click on the EXPORT REPORT function and follow the instructions to save or open the file.