The average car is driven about 12,000 miles per year. Since a 2009 car would be about 3 years old now; it would typically have about 36,000 miles on it. But some people drive twice that much each year; while others drive half of the national average. So you'll find 2009 model cars with as little as 18,000 or fewer miles on them; and you'll also find 2009 cars with as many as 72,000 miles on them. Most of the cars you find will have mileage that is somewhere between those extremes.
There is no "should" about the number of miles on a car. Some people think that the less miles a car has on it; the better condition it will be in and the longer it will last. But this is not always true. The way a car has been cared for and maintained can be more important than how many miles it has on the odometer. Freeway driving is considered to be the easiest type of driving that a car can have. City stop and go driving, and short trips are the hardest kind of driving a car can have. Experts are more interested in the condition of a car than how many miles it has on it.
I bought my present car when it was 2 years old; and it had 58,000 miles on it. This car was used for a 50 mile commute each way to work on all freeway driving. I was thrilled to find a car that had such good usage; and was not at all put off by the high miles. And it has turned out to be the best, most reliable and longest lasting car I have ever owned.