The global expenditure on research and development is roughly one trillion dollars a year (for the purists, the number is $994,424,038,000) according to a review of the State of Science 2008 in Seed magazine. Countries spend on average 2.3% of their GDP on scientific R&D. The U.S. accounts for slightly more than one-third of all expenditures.
There are 5.4 million Americans working in science and engineering today compared to 3.3 million a decade ago, and fewer than 200,000 in 1950.
I'm still reading the various parts of the review, which is the first of an intended annual series, and each section is compelling.