Did I see the same chart you did? I went back and looked, all I saw was "Q1" and "Q3" labels while the data showed all four quarters, but only half were labelled. It /was/ missing a Q4 though at the end.
All the quarters from Q1 2005 through Q4 2014 were plotted. The axis labels do not show all of them due to space constraints. Apologies that this was confusing, I will make sure to add all the tick marks and labels in the future.