Answer based on context:

As of the census of 2000, there were 218,590 people, 79,667 households, and 60,387 families residing in the county.  The population density was 496 people per square mile (192/km²). There were 83,146 housing units at an average density of 189 per square mile (73/km²). The racial makeup of the county was 86.77% Race (United States Census), 9.27% Race (United States Census), 0.23% Race (United States Census), 1.52% Race (United States Census), 0.06% Race (United States Census), 0.69% from Race (United States Census), and 1.47% from two or more races.  1.91% of the population were Race (United States Census) or Race (United States Census) of any race. 22.5% were of German people, 13.1% Irish people, 9.8% Italian people, 9.2% English, 8.1% "American" and 6.0% Polish ancestry.

How many more housing units were there than houses?
3479