Monday is Labor Day in the United States, the holiday that celebrates the economic contributions of workers. Measured as a share of the national economy, though, that contribution is less than anytime since 1947. Employee compensation has been falling for decades, down to about 42.5% of GDP at the end of the last quarter. Blame robots and offshoring, but also the mysterious fact, attributed to everything from de-unionization to tax policy to a lack of investment of education, that gains in productivity haven’t translated into higher wages.

Oh, and if you’re wondering about where at least some of those disappearing wages have gone, this chart offers a clue: