Comment by dublinben

Here is total employment for "Computer Systems Design and Related Services" going back all the way to 1987. This is the best category I can find that includes data over a decade+ time frame.

https://fred.stlouisfed.org/series/IPUMN54151W200000000

This category is defined by the BLS as "establishments primarily engaged in providing expertise in the field of information technologies through one or more of the following activities: (1) writing, modifying, testing, and supporting software to meet the needs of a particular customer; (2) planning and designing computer systems that integrate computer hardware, software, and communication technologies; (3) on-site management and operation of clients' computer systems and/or data processing facilities; and (4) other professional and technical computer related advice and services."