The good news is that you can track those shares with Facebook’s Insights for Your Domain. Follow theses simple steps:
Step 1: Go to the Facebook Insights Dashboard. Go to http://www.facebook.com/insights/
Step 2: Get the Insights for Your Domain Meta Tag. Click the green “Insights for Your Domain” button in the upper-right of the dashboard.
Step 3: Install Meta Tag on Your Site. Access the HTML code for your site’s root page, and paste the copied meta tag in between the <head> and </head> tags. Upload the edited page to your site’s server. (In reality, there will be a lot more code in your header section than shown in the example below. If you are unfamiliar with editing HTML, see your site’s webmaster.)
Verification of the meta tag installation may take some time, so be patient. In some cases, if you are not the admin who set up the page originally, your request to claim the domain may be denied. In that instance you will need to have the original admin follow the steps above (or use their login).
If your tag is successfully verified, sharing data should begin to be available after about 24 hours.
One more thing: You don’t access the Insights for Domain stats from your Page’s own Insights dashboard. You will check your share statistics at http://www.facebook.com/insights/ , where a new “Domains” section will appear.