Residential air conditioning was close to zero percent until after WWII. https://www.smithsonianmag.com/smithsonian-institution/unexpected-history-air-conditioner-180972108/ Household AC grew to 50% by 1970 and 90% by 2017. It grew from 88% in 2011 to 91% in 2019. http://www.freeby50.com/2011/08/percentage-of-homes-with-air.html https://www.eia.gov/consumption/residential/reports/2009/air-conditioning.php https://www.bloomberg.com/news/articles/2019-07-10/why-we-always-fight-over-air-conditioning The increased level of air conditioning is largely driven by the increased level of air conditioning included in new … Continue reading Good News: 91% of US Homes are Air Conditioned