The taller bars represent page views while the shorter, darker blue bars show unique visitors on any given day. For instance on Easter Sunday, 16,565 pages were viewed (the home page or a posting) by 10,155 different people.
Typically, specific postings represent about 2/3 of the traffic. I have no way to know how many people scroll down to read the comments, but it is certainly not insignificant. More importantly, it is about what we learn from each other.
I don’t pay much attention to stats, but it is nice to know.