This is a standard French term to categorize respondents in surveys. I've never seen it in English stats. But the word exists. See
see http://en.wikipedia.org/wiki/Intellectual_worker
An "Intellectual worker" (brain worker or knowledge worker) is anyone employed due to their knowledge in a subject matter, rather than their ability to, for example, perform manual labor. It includes those in the information technology fields, such as computer programmers, systems analysts, technical writers and so forth. The term can also refer to people outside of information technology but who nevertheless are hired for their knowledge of some subject, such as lawyers, teachers, and scientists.
The term "knowledge worker" was first used by Peter Drucker in his 1959 book, Landmarks of Tomorrow.