Only 0.9% of the American population has earned their doctoral degree, according to the U.S. Census Bureau's 2010 report. Earning such a degree puts you in an elite academic category, but only a few careers will require that PhD after your name. Here are six jobs for which earning your PhD will be a requirement. (To see the impact of your education, check out How Education And Training Affect The Economy.)

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1. Chief Scientist - $157,168
This applies for any science discipline, and this job is sometimes referred to as a Principal Investigator. The average salary ranges between $115,951 and $198,385, reflecting the years of study invested and the high degree of specialty.

At its simplest, the job of a Chief Scientist is to lead and carry out scientific research. They may be involved in the research and development (R&D) of new drugs or technology.

2. Professor - $82,374
Most professorships will require the candidate to have successfully defended their doctoral thesis. However, in business, law and medicine, sometimes real world experience may be sufficient without a PhD. This job is considered by many to be the most direct application for a completed doctoral degree – after spending so many years in academics, successful PhD graduates certainly know their way around the system.

Some professors focus on teaching, while others must find a balance between their time in the classroom and their own research and publications. An additional upside to this career is the possibility of tenure, which ensures that the professor cannot be fired without just cause and due process. This allows for a much greater stability in employment. (For more on teaching, see Academic Careers In Finance.)

3. Anthropologist - $44,756
While a PhD is not required for all levels, it is for most research positions. Anthropologists may also work concurrently as assistant professors or lecturers. While the average is a bit lower than the other jobs on this list, those with a PhD would likely fall in the top 10% of the salary range, for which the salary is significantly higher at $87,890, according to the Bureau of Labor Statistics (BLS).<br/>

Anthropologists study the origins and behavior of humans. They investigate earlier civilizations for clues as to how they lived, worked and evolved.

4. Astronomer/Astrophysicist - $81,208
These scientists observe, research, and interpret celestial and astronomical phenomena, according to Payscale. More than half of the professionals in this field are employed by the Federal Government or scientific R&D firms. They apply their knowledge of the universe to scientific and technological advancement. According to the BLS, almost all astronomers do research, although some do purely theoretical work. (To help students with the cost of going to school in one of these profession, read Students, Get More Bang For Your Textbook Dollars.)

5. University Deans, University V.P.s and University Presidents - $76,528
Tenured professors may have the chance to advance to be one of the top-ranking officers of the university. For those at a four-year institution, a PhD will be a requirement (though not usually for a two-year school). Each of these positions is responsible to some extent with the direction of the school, the marketing, the recruiting of new students, and hiring and overseeing faculty members.

6. Federal Reserve Board of Governors - $67,461
There are seven member of the Board of Governors of the Federal Reserve System. They are nominated by the President and confirmed by the Senate, according to the Federal Reserve website. Ben Bernanke is currently serving his second term as the Chairman of the Board. Dr. Bernanke earned his PhD in 1979 in economics from MIT, and went on to be a Professor of Economics at Princeton. As evidenced by this and some of the other jobs in this list, being a professor opens doors to many high-powered careers – and being a professor requires a PhD. (To learn more about Ben Bernanke, check out Ben Bernanke: Background And Philosophy.)

The Bottom Line
Earning a PhD isn't for everyone; in fact, only a very small percentage of the population will ever achieve this prestigious degree. However, for those who do, there are some highly sought-after careers that will be available to you. (For time on cutting the cost of grad school, read Attend Grad School For Free.)