U.S. labor productivity has been stagnating over the last few years and is expected to decline this year for the first time in three decades, according to the Dallas Federal Reserve, and some employers are blaming the stalled productivity on millennials playing on their smartphones.

“We have a serious productivity problem with office workers and estimated that less than 50 percent of their time is spent on value-creating business activities. The younger workers are often off task, engaged on social media, on the internet, texting on phones and other unproductive activities,” said one comment at the Dallas Reserve’s website.

Federal regulations also get blamed for the productivity drop. For example, employers blamed President Barack Obama’s new rule that requires overtime payments to salaried supervisors earning under $47,476 per year. That drives up costs, the employers complained.

The bad economic news was underlined by latest Dallas Fed monthly economic survey, which found that a measure of future work, the “New Order Index,” fell by 20 points to a negative -14.9.

Amid 230 years of economic expansions and recessions, U.S. productivity has expanded almost every year, allowing higher wages and greater wealth. America’s rising productivity has historically been attributed to new technology, management practices and to workers becoming more educated and acquiring greater skills. But since 2009, U.S. labor productivity — as measured by total annual production divided by hours worked — has flatlined.

Kevin Wilson, at Seeking Alpha, refers to this as a “conundrum,” because the information-technology and robotics revolutions should be boosting productivity. Wilson blames falling productivity on “the drag from inefficient educational institutions” contributing to workers becoming less educated and skilled, effectively slamming the federal “Common Core” curriculum and various politically correct universities,

The IT revolution — as part of the progression of better communications from the pony express, to railroad, to telegraph, to telephone, to fax, to text, to Internet, and now to social media — has obviously increased productivity and boosted employment. The “robotics revolution” started with Henry Ford’s first assembly line was in 1913. The new automation increased productivity and created millions of high-paying American manufacturing jobs.

But the annual growth of U.S. productivity peaked in 1970 at a positive 2 percent a year and then trended down to a positive 1 percent in 2008. But it has collapsed since 2009, with negative readings for the last two quarters.