WASHINGTON (MarketWatch) — It’s tough to read much in the latest quarterly swings in productivity data, but taken over the last four years, they paint a fairly dismal picture of the potential for growth from the U.S. economy.

The latest report from the Labor Department showed that productivity fell 1.8% in the fourth quarter. For the year, productivity grew just 0.8%.

That’s not a new trend. Since the recession’s end, productivity hasn’t surpassed a meager 1% in any year. There are different theories around to explain this phenomenon, including the lack of investment. Also see: The third industrial revolution is basically dead

A quick estimate of the growth potential of the U.S. economy is just the sum of productivity growth plus the growth in working-age population.

As the chart shows, it’s not much.

Even more sobering is the fact that the working-age population growth is set to decline — from roughly 0.5% right now, to just 0.2% in 10 years’ time.

In 2000 — the last year, incidentally, that there was growth of over 4% for the U.S. economy — the working age population grew 2.1%.

Stephen Stanley, chief economist of Amherst Pierpont Securities, says this explains the apparent paradox between the sharp drop in the unemployment rate and the continued mediocre growth of the U.S. economy.

“More broadly, I believe that it means the economy, both labor and product markets, has a lot less slack than generally presumed, so that 2015 real GDP growth in the 2½% to 3% range would probably generate a rise in wage and price pressures later this year,” he said in a note to clients.