To review your Broadcast analytics you will need to visit the settings section.
From here click Explore Analytics:
Now we need to view the Broadcasts instead of the Messages by changing from the selector:
The default view is the Chart and the default time setting is the Last 7 Days
Hovering over a broadcast displays some further information:
You can change to a Table view and also adjust the Date Picker. This will allow you to also download the Data as a .CSV file