The graph is pretty self-explanatory. It shows the number of visits Facebook has sent to TPM over the last 24 months. Before March 2009 the number was basically negligible. But the growth over this period has been quite dramatic.
To some degree this is simply a reflection of Facebook's massive growth over recent years. But the break-out growth also tracks pretty closely to when we set up a "fan" page at Facebook (now with over 34,000 fans) and began more systematically incorporating Facebook sharing tools into our basic story template.
To give you some additional perspective, last month Facebook accounted for 5.9% of the visits to TPM and it was the largest outside referrer to the site by a longshot. By way of contrast, last February it was 2.3% of the visits and the 5th largest outside referrer. Last month, Twitter, which we also use aggressively to distribute our news stories, accounted for 1.7% of the visits to the site.