From the Mozilla website, and obviously a part of their sales pitch.  I picked up that the calendar arrangement of the squares is in fact correct for 2006.  Its getting the small things right that help make good infographics.

An independent study shows that, in 2006, IE users were vulnerable to online threats 78% of the time. Firefox users? Only 2%.

“At risk” defined as publicly available exploits with no patch. Source: “Internet Explorer users Unsafe for 284 Days in 2006” Brian Krebs, Washington Post, 1/4/2007