Another good question is how many foreign born students come here on student visas and study STEM and how many of them get H1B visas?
Another good question is how many H1B visas go to teachers, nurses, and management/professional?
The vast majority of H1Bs over the years have been STEM related although I have been told that nurses and doctors are frequently included.
I don’t know the exact numbers, but a lot of the undergraduate and graduate students in my courses seem to receive H1B or resident alien status. Students will bring their wives here and they enroll in STEM programs after getting here and the gov is getting ready to include spouses of H1Bs for H1B status, automatically.
I don’t recall it falling off after 2000, in fact it seems to have been growing since then. In some cases the H1Bs are hired to learn the specific jobs and processes in anticipation of the company then shipping their operations to the H1B’s home country and the H1Bs along with the jobs.
In these cases, the jobs are still occupied by the foreign worker and american workers who trained them are left out on the street.
Managers are usually pretty careful not to “outsource” their own positions.