taxis

It's interesting to analyse a city by its taxis. Not because they're so knowledgeable about thei town -at day or night, but because the taxi density tells a lot about the city : types of flows, wealthiness...
I need information so please, send it along :
This is what I've come up with.
London : 19 000 taxis, 1 taxi for 315 people
Paris : 15 000 taxis, 1 taxi for 166 people
Prague : 7 000 taxis, 1 taxi for 157 people
Dusseldorf : 1 350 taxis, 1 taxi for 555 people
Marseille : 1 200 taxis, 1 taxi for 667 people.