Courtesy of Ezra Klein:
"There are a few things economists believe in our souls so strongly that we have a hard time actually explaining them," [MIT economist Jon Gruber] said. "One is that free trade is good and another is that health-care costs come out of wages." To put it another way: Economists are pretty united on this point. A firm's compensation for its workers is pretty static, and if relatively more goes to health-care costs, relatively less will go to wages, and vice-versa. But this isn't just a matter of theory. The [above] graph charts the percent growth in the median household income versus the percent growth in health-care costs since 1990.