The average fuel efficiency of vehicles sold in the country of Eldoria during the period 2005–2009 was 30 miles per gallon; the corresponding figure during the period 2000–2004 was 25 miles per gallon. The national average price of gasoline during the period 2005–2009 was $2.50 per gallon; the corresponding figure during the period 2000–2004 was $2 per gallon. The statements above, if true, best support which of the following conclusions about Eldoria?