This isn't a feature of Jetpack and beyond the level of support we can provide.
What you (or a developer) can do is create a simple app at http://developer.wordpress.com and leverage the Stats endpoint on our API ( https://developer.wordpress.com/docs/api/1/get/sites/%24site/stats/ )
You wouldn't want to directly call the API on each page load, so an app that would pull down the numbers and store it as a transient (maybe check once every 30m?), then output that value on the front end.
This is a cool idea. I'll see if I can put a tutorial together (that said, it could be this week or six months from now). I'll make a note to post an update here once/if I get to it.