The comedy team of Bob and Ray used to do a hilarious routine where a member of a group known as the Slow Talkers of America was interviewed by an impatient reporter, but being part of a slow-growing industry is no joke.

The financial information company Sageworks has just released a ranking of the 15 slowest-growing industries in the U.S. by sales growth over the past year.

A third of the sub-sectors on the list are related to manufacturing, an industry whose private companies have, overall, seen their rate of sales growth decline over the past few years, Sageworks noted. Most of the sub-sectors included on the list are related to one of three industries: manufacturing, wholesale, or retail trade. Metal and mineral wholesalers topped the list, seeing their sales drop 1.4 percent over the past year.

“Individuals looking for good business ideas and companies looking for strong investment opportunities may have cause to be wary of these industries,” said Sageworks analyst Libby Bierman. “The average privately held company is currently growing sales at a rate of nearly 9 percent per year. The industries on this list are growing sales at a rate less than 4 percent per year, and two of the sub-sectors are actually seeing sales contract.”

Accountants may want to advise their small business clients to avoid such industries (assuming, that is, they're not already part of one of these industries) or at least to adjust their revenue growth expectations accordingly.

Bierman cautioned that revenue growth, while it is an important measurement of a company’s (and industry’s) health, should always be considered alongside other financial metrics for a more complete assessment.

“It’s important to consider cash flow, liquidity and profitability, along with sales growth, when evaluating companies and industries," she said. "That would give a more complete picture of financial health and that market’s lifecycle stage. But, nonetheless, slow revenue growth is an immediate, easy red flag to identify.”