NOTE: The scale is based on the distribution of 1,386 reporting institutions by average salary for 2007-8. The figures cover full-time members of the instructional staff excluding those in medical schools. The salaries are adjusted to a standard nine-month work year. Percentile rankings are as follows: 1+ = 95th percentile; 1 = 80th percentile; 2 = 60th percentile; 3 = 40th percentile; 4 = 20th percentile. An average salary of $105,000 for the rank of professor in Category I institutions would be rated 3 because it falls between the 40th percentile ($103,691) and the 60th percentile ($115,750).