The number you propose - the number of charge stations divided by about 15 is indeed important - but only if one also takes into consideration the fraction of c

The number you propose - the number of charge stations divided by about 15 is indeed important - but only if one also takes into consideration the fraction of cars that are electric, versus those that use gasoline/diesel. To give an example: suppose that in some Kyoto district there are only 300 electric cars, versus around 5000 fuel-powered ones. Having roughly as many charge stations as there are gas stations wouldn't be an issue there. Also, once you have an operational charge point you can easily go parallel with stations, just like with gas pumps.