[eXpl0it3r]

Hehe this was an exercise question at my university. Look at the peaks again, zoomed in on a week, and you'll see that it's always on the weekend.

This most likely means that more people have IPv6 connections at home (weekend), than they do at their work place (throughout the week).

[wjoe]

You'll notice the same pattern on browser usage graphs - IE peaks during working hours, every other browser peaks on weekends and evenings.