"The World Database of Happiness, in Rotterdam, collects all the available information about what makes people happy and why. According to the research, married, extroverted optimists are happier than single, pessimistic introverts, and Republicans are happier than Democrats. Nurses enjoy life more than bankers, and it helps to be religious, sexually active and a college graduate with a short commute to work. The wealthy experience more mirth than the poor, but not much. Most people say they are happy, but perhaps that is because they are expected to be."