Bay Area is probably not a good metric because that would include Napa, Sonoma, etc. where you are more likely to find a farmer or a sommelier than a programmer.
Silicon Valley as a measure - 1% of the country's population but 10% of its programmers. So, 10x the national average of programmers.
Silicon Valley as a measure - 1% of the country's population but 10% of its programmers. So, 10x the national average of programmers.