U.S. manufacturing had its strongest year since 2004. The industry reported in December increased expansion over three months due to increases in orders and production, according to a report from the Institute for Supply Management (ISM).

The ISM report states that the factory index, a survey measuring factory activity, climbed from 58.2 to 59.7 over the past month and that a measure of new orders rose to 69.4, the highest recorded measurement of an expanding manufacturing sector since January 2004.

According to ISM, any reading above 50 points shows an increase in factory activity.

Tim Fiore, chair of the ISM manufacturing business survey committee, said he was optimistic about ISM’s latest report on the manufacturing industry.

“With a report like this, I can’t do anything but smile,” Fiore told the Kansas City Star.

The latest findings come as increases in domestic business investment, a rise in American household spending, and an improving global economy contribute to the manufacturing industry’s boom, Bloomberg reports.

Of the 16 industries reporting growth in December, the machinery, chemical, and computer and electronic products sectors reported the biggest gains.

The Federal Reserve notes that factory production increased by 2.4 percent over the past year, showing steady growth in the industry.

The report does not include the effect President Donald Trump’s tax reform initiatives would have on the industry, although the lower corporate tax rates are expected to facilitate more growth in the manufacturing sector.

Other industries, such as the airline industry, are already reaping the benefits of the newly-passed tax reform legislation. Southwest and American Airlines announced that they would each reward their employees with $1,000 bonuses due to the corporate income tax reduction.