Roughly 7.5 million Americans are unemployed and looking for work according to the U.S. Bureau of Labor Statistics, but many companies still struggle to fill key positions. Of more than 2,000 employers surveyed by CareerBuilder, nearly 60 percent say they have job openings that stay vacant for 12 weeks or longer. For companies with 50 or more employees, the number rises above 70 percent.

That affects businesses because it creates unnecessary costs and reduces the efficacy of companies' existing workforces. CareerBuilder reports that the average HR manager incurs more than $800,000 per year in costs from extended vacancies, and 45 percent of companies say extended openings hurt productivity. Even more concerning, four in 10 companies say that long-term vacancies have increased voluntary turnover, which means that failing to fill open positions beget more of them.

Thus, organizations might have to consider lowering their recruitment criteria and focusing on upskilling people into hard-to-find positions. After all, CareerBuilder reports that while 57 percent of workers say they want to learn a new skill set to land a better job, half of them can't afford to do so. And the cost of higher education could make company-provided skills training preferable to university or technical programs.

For occupations with more average monthly job postings than hires, that will hold especially true. Some examples from CareerBuilder include internists, truck drivers, marketing managers, information security analysts, web developers, industrial engineers, product promoters, sales managers, HR managers, and financial managers.