Well, the thing is that, the congestion charges, they were introduced first as a trial, so they were introduced in January and then abolished again at the end of July, followed by a referendum, and then they were reintroduced again in 2007, which of course was a wonderful scientific opportunity.
Lieta tāda, ka sastrēgumu nodeva sākotnēji tikai ievesta kā izmēģinājums, tādēļ tā tika ieviesta janvārī un tad atkal atcelta jūlijā beigās, kam sekoja referendums, un tad 2007. gadā tā tika atkārtoti ieviesta, kas, protams, bija lieliska zinātniska iespēja.