As of the census of 2000, there were 18,812 people, 7,402 households, and 5,477 families residing in the county.  The population density was 55 people per square mile (21/km²).  There were 10,319 housing units at an average density of 30 per square mile (12/km²).  The racial makeup of the county was 51.45% Race (United States Census), 41.90% Race (United States Census) or Race (United States Census), 0.20% Race (United States Census), 0.66% Race (United States Census), 0.04% Race (United States Census), 0.82% from Race (United States Census), and 0.92% from two or more races.  2.16% of the population were Race (United States Census) or Race (United States Census) of any race.. How many more households were there than families residing in the county as of the census of 2000?