Click on your HP name at the top of the page in black. Once the drop down menu appears click on (my account).
You should see statistics highlighted near the top and towards the left. Move towards the right and click on "Traffic Sources".
You should see a list of all the traffic sources or websites readers have come across your hubs. You won't be able to tell (who) it was or if they shared it to that site. However you'll know which sites people have used.