BOSTON ( TheStreet) -- Last month the story about the death of an adjunct professor from Duquesne University in Pittsburgh went viral. It was not so much the death of Margaret Mary Voitko at age 83 that tugged on the collective conscience of the public, but her life as a vastly underpaid and arduously overworked adjunct. Voitko had been teaching French at Duquesne for a quarter-century before dying Sept. 1. Her position, which was contract, offered no benefits and approximately $3,500 per three-credit course -- meaning her annual net salary reached barely $25,000 even during those times she was teaching three classes a semester. By contrast, the president of the University gets a yearly salary of $700,000 and full benefits, while college tuition and fees have increased by 440% in the past 25 years (four times the rate of inflation). "Contingent faculty" such as Voitko -- which include part-time teachers, non-tenure track full-time teachers and graduate assistants --make up 75% of higher education faculty of U.S. universities, with part-time faculty making up just over half. A 2010 survey by the magazine American Academic found that though 57% of adjuncts enjoyed their jobs, the exact same percentage was dissatisfied with their income. As it turns out, the paltry pay and lack of benefits that defined Voitko's position as an adjunct is far from rare. The national average pay reported for adjuncts is just $2,900 per three-credit course, which amounts to an average hourly wage of $8.90. The overall range of pay among adjuncts varies widely, though. Some have reported earning less than $1,000 per course, while one adjunct reported earning $12,575 for a course taught at Harvard University (Harvard adjuncts, at approximately $11,037 per course, are paid significantly above the national average). At other top-tier universities, the average pay per three-credit course is $4,750. Some factors that affect pay for adjuncts are location of the university (urban or rural), whether it is a community college and whether adjuncts are represented by a union. Those at smaller, rural, two-year institutions average about $1,808 per three-credit course. In California, where faculty at four-year and two-year institutions tend to be unionized, the average pay is $3,888 per course.