question: How many members are there in the cooperative that partnered with Mesa Citrus Growers Association during 1920s?
answer: 6,000
context: Title: Sunkist Growers, Incorporated
  Passage: Sunkist Growers, Incorporated is an American citrus growers' non-stock membership cooperative composed of 6,000 members from California and Arizona.  It is currently headquartered in the Valencia neighborhood of Santa Clarita, California.  Through 31 offices in the United States and Canada and four offices outside North America, its sales in 1991 totalled $956 million.  It is the largest fresh produce shipper in the United States, the most diversified citrus processing and marketing operation in the world, and one of California's largest landowners.
  Title: National Corn Growers Association
  Passage: The National Corn Growers Association (NCGA) is an association that represents and advocates for the interests of corn growers in the United States.  It is distinct from the American Corn Growers Association, a competing organization set up in 1987.
  Title: Mesa Citrus Growers Association
  Passage: The Mesa Citrus Growers Association is a citrus growers association located in Mesa, Arizona.  It was founded in the 1920s to take advantage of the growing citrus industry in the region.  During this time, it partnered with Sunkist Growers, Incorporated, in a building that operated until 2010.
citations: Sunkist Growers, Incorporated Mesa Citrus Growers Association