听力原文：Seems like there is good news for Americans who like to tip one bacchic at happy hour or relax with a glass of wine after work. A recent study by two economists shows drinkers earn more than teetotalers. In fact the data that published in a journal of labor research shows drinkers earn 10%-14% more than people who avoid alcohol altogether. The researchers say this disparity in pay might be explained by the fact drinkers have wider social networks. They argue this enables drinkers to get better jobs and business opportunities, truly increase social capital. But the study has its critics, they point out the researchers founded their work with money from libertarian think tank the Reason Foundation. That group has been fighting in- creased regulation and taxation of alcohol around the country. The authors of the study do point out social drinking has its limits. Having more than 21 servings of alcohol a week they say actually reduces earning potential. One could say all things in moderation. Why do drinkers earn more than teetotalers according to this passage?