Too late. I've already got your data! But sampling around here I see 10 stations with only one being urban but it is is Montreal which has 5 of the stations. Thus the probability of using the urban charger is
p(u) = p(u | M)p(M) = p(u | M)[p(M | m)p(m) + p(M | e)p(e)]
in which p(u | M) is the probability of using the urban charger given that you are in Montreal, p(M) is the probability that you are in Montreal, p(M | m) is the probability that you are in Montreal given that you live in Montreal and p(m) is is the probability that you live in Montreal. p(M | e) is the probability tat you are in Montreal given that you live in Estrie and p(e) is the probability that you live in Estrie. So taking Montreal/Estrie as representative of Canada I calculate, using some reasonable numbers for the relative populations of the city and country, p(u) = 0.132 and thus weight your urban time by that. This gives me a corrected average time of (0.132*30 + 0.868*15) = 16.98 minutes. I'll use that. Note that it is not atypical of what the rest of the survey shows.
The silliness above is there to be illustrative of what one can get into if trying to analyze deeper than what the available data allows or than the investigation requires.