i think it will help you to find your answer
http://en.wikipedia.org/wiki/Electricity_pricing
or
http://shrinkthatfootprint.com/average-electricity-prices-kwh
http://en.wikipedia.org/wiki/Electricity_pricing
or
http://shrinkthatfootprint.com/average-electricity-prices-kwh
Those prices are VERY outdated.
Anyone have some more recent pricing/stats?