World population doubled from 3 to 6 billion in 40 years

Evidence

The world’s population was 3 billion in 1959 and doubled to 6 billion over the next 40 years. Currently it is increasing by about 1 billion every 15 years, soaring toward an estimated 9 billion by 2044 (U.S. Census Bureau, 2015a). — Albert Bandura, Moral Disengagement, 2553