From the drop-down menu, there are two types of Email Campaign Statistics you can export (Fig 1):

• Export Summary Statistics 
• Export Detailed Statistics

Fig 1

After selecting the Email Campaigns you want reports on, select either Export Summary Statistics or Export Detailed Statistics and click the Go button. 

The Email Campaign Statistics page will reload with a notification stating your file is ready for download (Fig 2). 

Fig 2

Click on the link to download a CSV file containing your statistics.