The number of chickens produced annually in US has increased by 1,400% since 1950
"The number of chickens produced annually in the United States has increased by more than 1,400 percent since 1950 while the number of farms producing those birds has dropped by 98 percent."
Philpott, Tom. "What Has Massive Breasts, a Weak Heart, and a Lifespan of 42 Days?" Mother Jones. Jun. 12, 2012. http://www.motherjones.com/tom-philpott/2012/06/georgia-group-gives-bird...