As of the census of 2000, there were 45,087 people, 15,867 households, and 11,424 families residing in the county.  The population density was 87 people per square mile (34/km²).  There were 17,703 housing units at an average density of 34 per square mile (13/km²).  The racial makeup of the county was 57.14% Race (United States Census) or Race (United States Census), 38.70% Race (United States Census), 0.23% Race (United States Census), 0.26% Race (United States Census), 0.02% Race (United States Census), 2.76% from Race (United States Census), and 0.89% from two or more races.  6.17% of the population were Race (United States Census) or Race (United States Census) of any race.
Question: How many more housing units are there than households?
Answer: 1557