Elon Musk squeaked into the top 50 on Glassdoor's 2018 list of the 100 best CEOs, as rated by employees. He landed at No. 49 on the career website's list, with a 94 percent approval rating from his employees at the Hawthorne, California-based space exploration firm, SpaceX.

Unsurprisingly, he didn't make the list for his other company, the Palo Alto, California-based electric car maker, Tesla. The entrepreneur moved to lay off 9 percent of his workers at Tesla earlier this month. 

Musk isn't the only controversial CEO to make the list. Coming in at No. 16 is Facebook's Mark Zuckerberg, who has come under fire in the wake of the Cambridge Analytica scandal, in which the now-defunct political data firm harvested information from millions of Facebook users. Zuckerberg fell slightly in the rankings from the 2017 list, when he sat at No. 10.

Glassdoor allows employees to indicate whether they approve of their company's CEO when they write a company review. The website weighs the quantity of approval ratings and the quality of reviews when determining the list. A 2016 report by Glassdoor found that factors such as high company profit, good company culture, and relatively lower CEO compensation all predict higher CEO approval ratings.

Here are 2018's top 10 CEOs:

1. Eric Yuan, Zoom Video Communications, 99 percent approval rating
Employees cite management that really cares about employees and a fun, vibrant office culture as their favorite parts of working for the videoconferencing company. The free food always lying around the office doesn't hurt.

2. Michael Mahoney, Boston Scientific, 99 percent approval rating
Management's willingness to listen to employees' feedback has been a shining achievement. Workers are also hooked on the company's commitment to its mission: saving lives with its medical devices.

3. Daniel Springer, DocuSign, 99 percent approval rating
DocuSign, which offers electronic signature software, provides a healthy work-life balance and competitive salary and benefits packages, say employees.

4. Lynsi Snyder, In-N-Out Burger, 99 perecent approval rating
People who don't always associate the fast food industry with great work environments should talk to workers at this West Coast burger chain. Employees praise the friendly work atmosphere and good pay.

5. James Downing, St. Jude Children's Research Hospital, 98 percent approval rating
Employees feel like the company truly wants them to succeed, in their personal and professional lives. They also feel empowered by the company's mission, helping treat children with life-threatening diseases.

6. Corey Schiller and Asher Raphael, Power Home Remodeling, 98 percent approval rating
Workers love the multitude of opportunities for growth, including earnings.

7. Charles C. Butt, H-E-B, 98 percent approval rating
Employees speak highly of the opportunities for advancement and the company's flexibility to let workers adjust their schedule to their life. This isn't a surprise for the Texas-based grocery store chain that played an integral role in helping communities affected by Hurricane Harvey.

8. Jeff Weiner, LinkedIn, 97 percent approval rating
Weiner is the highest-ranking CEO from a social networking giant. His employees love the perks and benefits offered, which makes sense for a company whose business is employees themselves.

9. Colleen Wegman, Wegmans Food Markets, 97 percent approval rating
Employees rave about benefits, flexibility, and a supportive culture at a grocery chain with one of the best brand reputations.

10. Marc Benioff, Salesforce, 97 percent approval rating
Reviewers look forward to going to work at a company that strives to treat all employees as one big family and offers plenty of opportunities to learn and grow.