According to U.S. Census 2013 data, 1.68 percent of Americans over the age of 25 have a PhD. This equates to approximately 2.5 million people. People with professional degrees such as MD or DDS make up 1.48 percent of the U.S. population, making the total percent of Americans referred to as doctors equal to 3.16 percent.
The vast majority of adults in the U.S., over 88 percent, have a high school diploma or additional education. Around 31 percent of the population has a bachelor's degree or higher, and almost 12 percent have a master's degree or higher.
Students take twice as long to earn a PhD as a bachelor's degree, or an average of 8.2 years. The average age of a PhD graduate is 33. Most PhD students must assist in teaching undergraduate classes and grade papers of undergraduates. The dropout rate for PhD students is 43 percent. The number of men holding a PhD is approximately 1,678,000, compared to 817,000 women.
While many PhD programs offer scholarships and stipends to cover tuition and living expenses, 40 percent of PhD students graduate with debt averaging $37,000. According to the Bureau of Labor Statistics, PhD and professional degree holders enjoy the highest wages and the lowest unemployment rates.