Why may there be a Link between Wealth and Energy Consumption?

-Take USA, Iconic Example. People in USA have a Higher Standard of Living so therefore will have a Bigger % having Electricity and Heat, as they can Afford it, and Want it - more Energy Consumed. [High Energy per Person] -Take Mali. People here have a Lower Standard of Living and so therefore have less People having Energy - as they can not Afford it, or Make it. Therefore leading to Lifestyles not Dependent on High Energy Consumption