Are you still using the classic Garmin Connect? If so, getting what you want is pretty simple. Go to the Reports page. Ensure that Progress Summary is the report type. Change the report to Report on [This Year] for [Running] to get a summary of your running miles this year.
You could also use the Activity Distribution report for this year to get a summary of the results for each activity type.
If you are on the modern Garmin Connect, I can't really help you. I can only see a few of those pages, and I'm not even sure if the reports page exists there. It doesn't really matter though as you should be able to access the classic reports page for a while.
Travis