On the Connect main page (dashboard), click on the + with the dashed lines around it to add a new item. Select Report from the flyout menu. For type of report select Total Distance. If you hover over a bar on the graph it shows your mileage for that time period. Set your time period for last 6 months or last year and you can see mileage by month.

Full disclosure - I usually use RWGPS to view my data.