My city is not listed!
While we all like to think that our suffering is the worst, reality is that if your city is not listed is because it is not the worst.
According to the article it seems that from the questions they were able to gauge how much the traffic affects the people and the economy, How frequent there are traffic jams are and how long the peak hour lasts.
E.g. Peak time in Toronto is awful but comparatively speaking it is fairly the same as a regular non peak time business day in Mexico City. This despite the fact that each car in Mexico city MUST stay home one day of the week (or two under some circumstances).