Updated: Aug 28, 2020
You can actually check this figure for yourself. Below are the instructions to check that figure for a Microsoft Outlook account. Please note that Insights only works on a Microsoft Exchange account, not an account that you are using Outlook to manage.
Go to your Home tab, click on Insights, then find the tiny little graph icon and click on that.
Once you get this screen click on the 'Collaboration' tab in the left hand green column.
When you get to the collaboration screen scroll all the way down to the bottom to the "Communication habits" screen where it will tell you how many emails you sent and read in the last four weeks.
You will of course have to do some basic division as they will only give you the data over four weeks, but I am sure you can cope with that.