“Postsecondary teachers instruct students in a wide variety of academic and vocational subjects beyond the high school level. Most of theses students are working toward a degree, but many others are studying for a certificate or certification to improve their knowledge or career skills. Postsecondary teachers include college and university faculty, postsecondary career and technical education teachers, and graduate teaching assistants. Teaching in any venue involves forming a lesson plan, presenting material to students, responding to students learning needs, and evaluating student progress. In addition to instruction, postsecondary teachers, particularly those at 4-year colleges and universities, also perform a significant amount of research in the subject they teach. They must also keep up with new developments in their field and may consult with government, business, nonprofit, and community organizations.

College and university faculty make up the majority of postsecondary teachers. Faculty usually are organized into departments or divisions, based on academic subject or field. They typically teach several different related courses in their subject—algebra, calculus, and statistics, for example. They may instruct undergraduate or graduate students, or both. College and university faculty may give lectures to several hundred students in large halls, lead small seminars, or supervise students in laboratories. They prepare lectures, exercises, and laboratory experiments; grade exams and papers; and advise and work with students individually. In universities, they also supervise graduate students’ teaching and research. College faculty work with an increasingly varied student population made up of growing shares of part-time, older, and culturally and racially diverse students.”
【许多hold the the rank of Professor 不是由University/college,而是由其它机构发工资的，因此他们的jobs不属于Postsecondary teachers类，但挣的比Postsecondaryteachers是只多不少的。】
你是想说“美国一流的研究人员”？不说美国名牌大学正教授了？
见：http://www.bls.gov/oco/ocos066.htm

【按WIKI（http://zh.wikipedia.org/wiki/%E5%93%88%E4%BD%9B%E5%A4%A7%E5%AD%A6）上说的：哈佛有2,400名教授，6,700名本科生和12,400名研究生。
这个2,400名教授就是你说的那个Postsecondary teachers。是哈佛的文法医商所有各科的总的教授数。这里面生物医学类的教授占多少呢？我懒得去查了，你可以去细查。按WIKI哈佛有20个包括生物医学的系所，按系的比例，生物医学类的教授占1/10　=　240名。而实际上，有哈佛大学教授头衔的是多少呢？10，000名以上！若假设其中一半是饶那样的正教授。就这一项你的计算就小了20倍！！】
对不起，你这个小20倍是怎么来的？10,000/2,400=20?
请提供【而实际上，有哈佛大学教授头衔的是多少呢？10，000名以上！】依据。不要懒的查，请给出你所说的在美国“有教授头衔”人有多少？是1.7 million吗？

“The term "professors" in the United States refers to a group of educators at the college and university level. In colloquial language, usage of the term may refer to any educator at the post-secondary level, yet a considerable percentage of post-secondary educators do not hold the formal title of "professor," but are instead lecturers, instructors, and teaching assistants.[7]

Educators who hold a formal title of "professor" (referred to as tenured/tenure-track faculty) typically begin their careers as assistant professors, with subsequent promotions to the ranks of associate professor and finally professor. College and university teachers that hold the rank of lecturer or instructor are not tenured/tenure-track faculty, typically focus on teaching undergraduate courses, and are generally not involved in research; neither are they typically involved in department and university decision-making. Professors may also hold special titles, such as professor emeritus (or emerita for women), given to those who continue to teach after retirement, or distinguished professor, given commonly to the top 1% of faculty members. Some faculty may additionally hold an endowed chair in which position is funded by donations from the university, private individuals, firms, or foundations.

Professors typically focus their efforts on research and teaching, with the balance of time spent between the tasks depending strongly on the type of institution. (For example, a doctoral-level university will almost exclusively demand research productivity--published articles and books--from its professors, while liberal arts colleges evaluate their faculty based on teaching ability and evaluations.)”

见：http://en.wikipedia.org/wiki/University_professor#United_States

【The rank of Professor is held by 29.5% of US academics，　NOT by US　postsecondary teachers。你应该是认得英文的，怎不知道这两者是不同的呢？】
如果要再精确一点那个数字应该是
29.5%/(29.5%+23.1%+22.4%)=39% 这个数字不影响我计算的结果。
“As of 2007, 23.1% of academics held the rank of assistant professor....As of 2007, 22.4% of academics hold the rank of associate professor....The rank of Professor is the highest of the standard academic ranks in the United States, and is held by 29.5% of US academics.”
见： http://en.wikipedia.org/wiki/Professors_in_the_United_States

说个错就那么难？你不是都说过了吗？