Utilize the input text as a context reference, choose the right relationship between 58 and California from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

In the first five years of the economic recovery, from 2009 through 2014, the richest 1 percent of Americans captured 58 percent of income growth, according to Emmanuel Saez, a University of California economist whose research Sanders uses.

Answer: location_of_formation