(The following is based on material written in 1996.) The Montreal Protocol on Substances that Deplete the Ozone Layer, signed in 1987 by more than150 nations, has attained its short-term goals: it has decreased the rate of increase in amounts ofmost ozone-depleting chemicals reaching the atmosphere and has even reduced the atmosphericlevels of some of them. The projection that the ozone layer will substantially recover from ozonedepletion by 2050 is based on the assumption that the protocol’s regulations will be strictlyfollowed. Yet there is considerable evidence of violations, particularly in the form. of the release ofozone-depleting chlorofluorocarbons (CFC’s), which are commonly used in the refrigeration,heating, and air conditioning industries. These violation reflect industry attitudes; for example, inthe United States, 48 percents of respondents in a recent survey of subscribers to Air Conditioning,Heating, and Refrigeration News, and industry trade journal, said that they did not believe thatCFC’s damage the ozone layer. Moreover, some in the industry apparently do not want to pay forCFC substitutes, which can run five times the cost of CFC’s. Consequently, a black market inimported illicit CFC’s has grown. Estimates of the contraband CFC trade range from 10,000 to22,000 tons a year, with most of the CFC’s originating in India and China, whose agreementsunder the Protocol still allow them to produce CFC’s. In fact, the United States Customs Servicereports that CFC-12 is a contraband problem second only to illicit drugs. According to the passage, which of the following best describes most ozone-depleting chemicals in 1996 as compared to those in 1987?