LSAT Logical Reasoning Question of the Day

While tablet computer sales have increased steadily over the last 2 years, we can expect a reversal of this trend in the near future. Since they became popular in the marketplace 5 years ago, 60 percent of tablet computers sold have been purchased by people from 18 to 25 years of age, and the number of people in this age group is expected to decline steadily over the next 15 years.

Which of the following, if true, would most seriously weaken the argument?