The document discusses the use of chlorofluorocarbons (CFCs) between 1915 and 2019. In 1915, CFCs were first synthesized but did not see widespread commercial use until the 1920s. By the late 1970s, CFCs accounted for over 55% of all aerosol spray propellants and around 25% of refrigerants. Their use and production has since been phased out and regulated due to their ozone-depleting properties.