NSF Study on Science and Engineering

The Science and Engineering Indicators is a huge set of data on US and international science and engineering. If you download the pdf it's full of charts and numbers. They also break down things in layperson terms such as:

College graduates who become teachers have somewhat lower academic skills on average than those who do not go into teaching.

In academic year 1999, between 23% and 29% of public middle-grade and high school mathematics and science teachers did not have a college major or minor in their teaching field.

In 2002, the average salary of all public school K-–12 teachers was $44,367, just about $2,598 above what it was in 1972 (after adjusting for inflation).