It pays to ask for more.

The average U.S. employee could be earning $7,500 more than they do per year on average, according to a study by job site Glassdoor, which compared the differences between the base salaries that people report they get with what the current market value of that same job was (that represents what people could be earning).

A big part of problem is that we don’t negotiate our pay. “With three in five U.S. employees acknowledging they did not negotiate their salaries, this new data suggests that many Americans could be earning more,” the report revealed. Indeed, a study 700 employers by Nerdwallet revealed that about three in four were able to increase their first salary offer by 5-10%; yet only 38% of the 8,000 college grads also questioned in the survey tried to negotiate their offer. Of those grads who asked for a higher salary, 80% were at least partially successful.

Also see: Male college grads immediately make more than their female peers

People in some jobs are likely way more underpaid — at least when you compare what they actually make with the market value for that job — than others. Here are the 10 most underpaid professions in America, according to Glassdoor.

1. Emergency Medical Technician
Potential Salary Growth: 21.9% or $7,771
Current Median Base Salary: $27,636
Current Market Value: $35,407

2. Certified Nursing Assistant
Potential Salary Growth: 21.3% or $6,505
Current Median Base Salary: $24,000
Current Market Value: $30,505

3. Research Assistant
Potential Salary Growth: 20.9% or $7,935
Current Median Base Salary: $30,000
Current Market Value: $37,935

4. Java Developer
Potential Salary Growth: 17.7% or $16,792
Current Median Base Salary: $ 78,000
Current Market Value: $ 94,792

5. Pharmacist
Potential Salary Growth: 16.5% or $23,261
Current Median Base Salary: $118,000
Current Market Value: $141,261

6. Web Designer
Potential Salary Growth: 15.5% or $9,508
Current Median Base Salary: $52,000
Current Market Value: $61,508

7. Software Engineer
Potential Salary Growth: 15.2% or $17,943
Current Median Base Salary: $100,000
Current Market Value: $117,943

8. Medical Assistant
Potential Salary Growth: 15.1% or $5,320
Current Median Base Salary: $30,000
Current Market Value: $35,320

9. Marketing Manager
Potential Salary Growth: 15.0% or $14,107
Current Median Base Salary: $80,000
Current Market Value: $94,107

10. Communications Manager
Potential Salary Growth: 14.8% or $13,334
Current Median Base Salary: $76,498
Current Market Value: $89,831

EMTs may top this list because demand for this job has jumped in recent years (see Moneyish’s story on opiod overdoses here) so employers are willing to pay more. But at the same time, many people who have been in the job for a few years haven’t negotiated to get big raises like the newcomers might be getting, explains Sarah Stoddard, a spokesperson for Glassdoor.

This all underscores that it is essential that people in all professions — and particularly those in the above professions, negotiate their salary for a new job or a raise if they want to stay in their current job. To begin, people should know what the going rate is for the position they’re in or applying for (you can find this out online at sites like Glassdoor.com, Salary.com, Indeed.com, and Payscale.com). This can help you know what kind of money you’re targeting.

Also see: Need a raise? This FBI negotiator shows you how

Another pro tip: Ask for a salary range rather than stating a single number, a Columbia University study shows. So if you want $55,000, you should state that you want a salary that is between $55,000 and $60,000.

Also see: 5 awesome work-from-home jobs that easily pay $100,000