Every month, millions of Americans leave their jobs, either because they are laid off or because they quit. While leaving work or quitting can be a step to a better job, most American workers likely seek stable, long-term employment.

Losing one’s job and being stuck in unemployment is far less likely in some occupations than in others. Those occupations that require high degrees of specialization, years of experience, and are in high demand tend to be highly stable jobs. Based on unemployment rates for hundreds of occupations provided by the Bureau of Labor Statistics, 24/7 Wall St. reviewed the 13 jobs with 0.5% unemployment or less. People who lose their jobs or otherwise leave these occupations either do not stay unemployed for long or retire from the workforce entirely.

Most of the jobs on this list require at least some formal education beyond a high school diploma, and many require doctorates, residencies, and licensing. Those jobs with low unemployment rates that do not require a college degree — such as construction and building inspectors and stationary engineers, usually require years of skills developed on the job. The highly specialized nature of these jobs means there is a smaller pool of potential applicants and workers are less replaceable as a result.

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Wages in these occupations that involve high skill work and require significant training tend to be much higher than the average wages across all occupations. The average annual U.S. wage is $48,320. Only one of the 12 occupations on this list — directors of religious activities — have a lower average annual wage. Meanwhile, eight of the 12 have average wages of more than $70,000, including physicians, who make over $200,000 each year.

Workers in many of these fields are not just in high demand because they have specialized knowledge, but also because their fields are growing. The BLS projects overall employment will increase by 6.5% between 2014 and 2024. While projections are not available for all of these 13 occupations, many are expected to grow as fast or faster than the national job growth rate. The numbers of employed dentists, dental hygienists, and physicians and surgeons are projected to grow at more than double the national rate.

Unemployment rates in many of these jobs may be so low because these occupations are not just stable, but can come in the later stages of a career. People who leave these jobs are more likely to retire rather than continue looking for work. The typical worker in only three of the 13 occupations on this list is younger than the U.S. median worker age of 42.3 years. The typical construction and building inspector is over 50 years old.

To identify the easiest and hardest jobs to keep, 24/7 Wall St. reviewed 2016 unemployment rates among workers in 565 occupations provided by the Bureau of Labor Statistics. Workers are considered unemployed based on the job they held most recently. Occupations with an experienced labor force of less than 50,000 were not included. An experienced labor force excludes new entrants or those entering the labor force for the first time. Estimated employment growth between 2014 and 2024, average 2015 wages, labor force totals, and typical education requirements for each job also came from the BLS.

These are the easiest jobs to keep.