Literally the author states it's unverifiable data:
The chart has unverified information "The average mineral content of calcium, magnesium, and iron in cabbage, lettuce, tomatoes, and spinach has dropped 80-90%
between 1914 and 2018 30,34,35,36,371. Asterisks indicate numbers could not be independently verified."
The chart has unverified information "The average mineral content of calcium, magnesium, and iron in cabbage, lettuce, tomatoes, and spinach has dropped 80-90% between 1914 and 2018 30,34,35,36,371. Asterisks indicate numbers could not be independently verified."