How do I get Count of Emails sent per month across all workspaces

hi

I would like to get count of emails sent by all the workspaces per month.

We would like to see the usage of Marketo per each month. (similar to the screenshot attached)

-Can someone help? 

Is it possible to get all the counts in one report?

OR

do I need to report for each workspaces separately and consolidate that in an excel sheet?

{we have about 25 workspaces on our account}

thanks

-Sree