The average monthly amount Isabella has spent on gasoline since 1990 is shown in the table.   Use the data in the table to complete the statements.  Let x be the number of years since 1990. The year 2005 corresponds to an x-value of .  The function that best models the data, with numerical values rounded to the nearest hundredth, is f(x) = x + 22.08.  Models have their limitations. For which year would this model not make sense to use?