Productivity in glass and glazing manufacturing has been a mixed bag over the last two decades, according to new data from the U.S. Bureau of Labor Statistics (BLS).

The BLS recently released its Multifactor Productivity Trends for Detailed Industries – 2015 report, which measures output per unit of combined inputs for 86 major manufacturing segments. Inputs include hours worked, capital and intermediate purchases.

[For’s analysis on labor productivity data, click here.]

According to the data, the glass and glass products industry, which is largely made up of flat glass, improved its multifactor productivity by 0.6 percent from 2014 to 2015.

On a near two-decade scale (from 1987-2015), multifactor productivity in the glass category improved 1.1 percent thanks to a slight increase in output combined with decreases in every input type.

Architectural and structural metals, which includes glazing and framing systems, went in the opposite direction. Multifactor productivity dipped 4.1 percent on a year-over-year basis thanks mostly to a notable increase in intermediate purchases and only a tepid increase in output.

But from 1987 to 2015, multifactor productivity in this category decreased just 0.3 percent as a 0.9-percent bump in output was the result of very slight upticks in each input category.

For perspective, 21 of the 86 manufacturing industries included in the report saw an increase in multifactor productivity in 2015. However, more industries saw productivity growth over the long term than short term, with 54 segments showing an increase from 1987 to 2015.