2000 22,151 1990 19,580 1980 19,612 1970 16,943 1960 17,015 1950 16,034 1940 14,412 1930 14,498 1920 14,806 1910 15,335 1900 16,388 1890 18,366 1880 20,092 1870 20,223 1860 19,549 1850 17,968 1840 13,349 1830 10,190 1820 10,763
As of the census of 2000, there were 22,151 people, 7,868 households, and 6,129 families residing in the county. The population density was 57 people per square mile (22/km²). There were 8,596 housing units at an average density of 22 per square mile (9/km²). The racial makeup of the county was 99.02% White, 0.03% Black or African American, 0.16% Native American, 0.22% Asian, 0.02% Pacific Islander, 0.09% from other races, and 0.47% from two or more races. 0.47% of the population were Hispanic or Latino of any race. 46.4% were of German, 19.4% American, 9.2% English and 8.5% Irish ancestry according to Census 2000.
There were 7,868 households out of which 37.60% had children under the age of 18 living with them, 66.00% were married couples living together, 8.00% had a female householder with no husband present, and 22.10% were non-families. 19.00% of all households were made up of individuals and 8.80% had someone living alone who was 65 years of age or older. The average household size was 2.77 and the average family size was 3.17.
In the county the population was spread out with 28.10% under the age of 18, 7.60% from 18 to 24, 29.20% from 25 to 44, 22.60% from 45 to 64, and 12.50% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 99.70 males. For every 100 females age 18 and over, there were 97.60 males.
The median income for a household in the county was $43,530, and the median income for a family was $50,171. Males had a median income of $33,998 versus $24,516 for females. The per capita income for the county was $18,624. About 4.70% of families and 7.10% of the population were below the poverty line, including 7.90% of those under age 18 and 9.70% of those age 65 or over.