What is the relationship between 58 and California in the context of the input sentence. Choose an answer from: 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