In the U.S., “professors” commonly occupy any of several positions in academia, typically the ranks of assistant professor, associate professor, or professor, the last commonly called “full professor”. The same terms are used outside the U.S., although they often denote different roles from in the U.S. system. Research and education are among the main tasks of professors, with the amount of time spent on research or teaching depending strongly on the type of institution. Publication of articles in conferences, journals, and books is essential to occupational advancement. As of August 2007 teaching in tertiary educational institutions is one of the fastest growing occupations, topping the U.S. Department of Labor’s list of “above average wages and high projected growth occupations,” with a projected increase of 524,000 positions between 2004 and 2014. In 2011, a survey conducted by TIAA-CREF Institute senior researcher Paul J. Yakoboski estimated that 73% of professors with senior tenure ranged between the ages of 60 and 66 and that the remaining 27% were above the age of 66. Yakoboski estimated that 75% of these professors have acknowledged that they have made no preparations for retirement due to the ongoing financial crisis and reluctance to leave their profession. A 2013 survey conducted by Fidelity Investments would echo similar results when the question about retirement came up.