If you’re a hiring manager and have seen several seniors among the sea of millennials in your applicant pool lately, don’t consider them anomalies or dismiss them based on age alone. Nearly one-fifth of Americans ages 65 and over are employed.

More elderly Americans are staying in the workforce than at any other point in the 21st century, according to a Pew Research Center analysis of Bureau of Labor Statistics data. In 2000, when Pew began studying older workers, 12.8 percent of older Americans said they were working full or part time. Now, 18.8 percent of older Americans -- about 9 million people -- have jobs.

Related: 3 Tips for a Millennial Manager Leading an Older Generation

Older workers were more likely to withstand the Great Recession than the general adult population. While 64.4 percent of all adults had jobs in May 2000, by January 2011, only 57.6 percent were employed, and today, 59.9 percent of American adults are working. Meanwhile, a greater proportion of Americans 65 and older are working than they were at any point since 2000, and the proportion has been increasing steadily since the turn of the century.

This phenomenon holds for all subgroups of the 65-plus cohort. Larger shares of Americans aged 65 to 69, 70 to 74 and 75-plus are working than before. And while the percentages of employed seniors are increasing, the proportion of those working part-time has decreased from 46.1 in 2000 to 36.1 today -- meaning that more are working full-time.

Men, despite being 45 percent of the 65-plus demographic overall, make up 55 percent of the 65-plus workers.

Related: This 100-Year-Old Woman Works 11-Hour Days and Says She Wouldn't Have It Any Other Way

Pew reports that management positions are the most common jobs that older Americans perform. But as for positions for which older adults more likely to be hired, rather than doing the hiring, legal and social service roles are most common. They are less likely to work in professions focused on computers and math, food preparation and construction, compared with other age groups. Adults aged 65 and older are becoming a greater percentage of the total American population. In 2010, 13 percent of U.S. residents were older than 65, compared to 9.8 in 1970. By 2030, when baby boomers range in age from 66 to 84, that proportion will likely increase to 20 percent, according to the U.S. Census Bureau.

While many companies are careful to avoid age discrimination, they also must hire the best person for the job to maximize returns. When looking for a new member for your team, keep this shift in mind. Note which types of roles may suit prospective employees who began their careers before the advent of today’s technology or may be less equipped for physically intensive tasks. Willing workers over 65 are on track to become even more common, and their resistance to retirement is a major opportunity for employers.