For the past while individuals who took the Narcissistic Personality Inventory test on this website were asked to enter what they majored in at college (if they did). Above is a graph of average narcissism across all the majors that had at least 25 data points (histogram of sample sizes) after some reduction (e.g. “Business Management”, “Business Administration” -> “Business”). The sample was 52% male and the average age was 40.03 years.
Nursing and Accounting which had lower end sample sizes are different with p < 10-5.
The individual data points can be downloaded here.