The great skills gap mystery continues. Despite millions of workers still looking for jobs, there are a wide variety of positions employers just can't seem to fill, new research shows.

A study by CareerBuilder revealed that more than a third of hiring managers currently have positions that have remained open for at least 12 weeks.

"Although the recession created an abundant pool of readily available, unemployed talent that still exists today, employers are struggling to find new employees for technology-related occupations, sales, health care and a variety of other areas," said Brent Rasmussen, president of CareerBuilder North America.

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Specifically, the toughest jobs to find qualified employees for right now are:

  • Sales representative
  • Machine operator/assembler/production worker
  • Nurse
  • Truck driver
  • Software developer
  • Engineer
  • Marketing professional
  • Accountant
  • Mechanic
  • IT manager/network administrator

As a way to ensure they always have a stockpile of qualified candidates for all their positions, regardless of whether one is open or not, more than 40 percent of those companies surveyed recruit throughout the year.

"The skills gap that exists for high-growth, specialized occupations will become even more pronounced in the years to come, prompting the need to place a greater emphasis on reskilling workers through formal education and on-the-job training," Rasmussen said.

The study was based on surveys of more than 2,000 hiring managers and human resource professionals, as well as job growth data provided by Economic Modeling Specialists.

Follow Chad Brooks on Twitter @cbrooks76 or BusinessNewsDaily @BNDarticles. We're also on Facebook & Google+. This story originally published on BusinessNewsDaily.