Marketing Cloud Recommendation KPIs

Hello experts,

I have a question about the recommendation KPIs. This Reco will be placed in a Welcome Mailing. This mailing was sent about 270 times. In the App Manage Recommendations the number of impressions is 10,615. This does not fit together! Can anyone explain how the number of impressions is formed? Also the number of the KPIs Click-Through Rate and Conversion Rate?

Thanks a lot!
Christiane