the calendar year. Data include vehicles which were retired during the year and vehicles that were registered in more than one State. In some States, it is also possible that contrary to the FHWA reporting instructions, vehicles which have been registered twice in the same State may be reported as two vehicles". (All italics added for emphasis.) Vehicles in Operation (VIO) In the year 2001, the National Automobile Dealers Association conducted a study revealing the average age of vehicles in operation in the US. The study found that of vehicles in operation in the US, 38.3% were older than ten years, 22.3% were between seven and ten years old, 25.8% were between three and six years old, and 13.5% were less than two years old. According to this study the majority of vehicles, 60.6%, of vehicles were older than seven years in 2001. This relatively high age of automobiles in the US might be explained by unaffordable prices for comparable new replacement vehicles and a corresponding gradual decline in sales figures since 1998. Also, many Americans own three or more vehicles. The low marginal cost of registering and insuring additional older vehicles, many of which are rarely used, could cause the study to be skewed as these vehicles are still given full weight in the statistics. The median and mean age of automobiles has steadily increased since 1969. In 2007, the overall median age for automobiles was 9.4 years, a significant increase over 1990 when the median age of vehicles in operation in the US was 6.5 years and 1969 when the mean age for automobiles was 5.1 years. Of all body styles, pick-up trucks had the highest mean age in 2001 (9.4 years), followed by cars with a mean age of 8.4 years and van with a mean age of 7.0 years. As SUVs are part of a relatively new consumer trend originating mostly in the 1990s, SUVs had the lowest mean age of any body style in the US (6.1 years). The average recreational vehicle was even older with a mean age of 12.5. For all body styles the mean vehicle age increased fairly steadily from 1969 to 2001. In March 2009, RL Polk released a study conducted between 2007 and 2008 which indicated that the median age of passenger cars in operation in the US increased to 9.4 years, and that the median age for light trucks