Plugin: Twitter Facebook Social Share
Shareaholic:
https://wordpress.org/plugins/shareaholic/How to track?
Ask yourself: Is this necessary?
http://torquemag.io/are-social-sharing-buttons-a-valuable-addition-to-your-...Aside from potential site performance issues that a sharing plugin could possibly introduce, there are psychological reasons that having a row of share buttons around your content could actually result in *fewer* shares.
Social proof: If your buttons all have zeroes on them, others are less likely to share with their networks. On the other hand, if every network has hundreds or even thousands of shares, people are less likely to share because why post something everyone has already seen?
Shareaholic is nice because it allows you to turn the counter off if you like, and it also displays related content from your site.