Demographics As of the census of 2000, there are 156,951 people, 55,384 households, and 43,531 families residing in the county. The population density is 107/km² (276/mi²). There are 58,919 housing units at an average density of 40/km² (104/mi²). The racial makeup of the county is 97.13% White, 0.46% African American, 0.43% Native American, 0.57% Asian, 0.03% Pacific Islander, 0.32% from other races, and 1.06% from two or more races. 1.24% of the population are Hispanic or Latino of any race.
There are 55,384 households out of which 39.80% have children under the age of 18 living with them, 68.50% are married couples living together, 6.80% have a female householder with no husband present, and 21.40% are non-families. 17.10% of all households are made up of individuals and 5.40% have someone living alone who is 65 years of age or older. The average household size is 2.80 and the average family size is 3.18.
In the county the population is spread out with 28.80% under the age of 18, 6.60% from 18 to 24, 31.70% from 25 to 44, 24.60% from 45 to 64, and 8.30% who are 65 years of age or older. The median age is 36 years. For every 100 females there are 102.10 males. For every 100 females age 18 and over, there are 99.70 males.
The median income for a household in the county is $67,400, and the median income for a family is $75,284. Males have a median income of $54,358 versus $32,073 for females. The per capita income for the county is $28,069. 3.40% of the population and 2.40% of families are below the poverty line. Out of the total people living in poverty, 3.60% are under the age of 18 and 4.50% are 65 or older.