It is estimated that, from the beginning of 1993 to the end of 1997, the average number of CD's bought by teenagers increased from 7 per year to 15 per year. During the same time period, the average number of video games purchased by teenagers increased from 6 per year to 18 per year. Assuming that in each case the rates or purchase are the same, in what year did teenagers buy the same average number of CD's and video games?

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