It's a good question: you can see a fairly granular breakdown of the workforce by industry [here](https://www.bls.gov/cps/cpsaat11b.htm). There are about 5.1 million people working in "Computer and mathematical occupations", the majority of whom are developers.
man a first look at that tree map made it seem strangely mis-represented... like there is no way there are that many dental assistants. Pro tip for viewers: zoom all the way out
