CA Does not Produces More Top Stem students

than other states. Actually, CA has slightly lower top STEM Asian students percentage wise comparing with nation. Asian and especially Chinese Americans dominates academic Olympiads. While 37% Chinese Americans live in California, only 20% top math students (based on USAMO/MOP qualifers) and 33% of USAPHO students come from CA, lower than the asian average nationally. 

Actually MA, NJ, CT, VA, Md, NC, WA and probably even TX and MI are just as good as CA if not better at producing top talented ABC STEM students.