size was 2.54 and the average family size was 3.14. The age distribution was 23.40% under the age of 18, 7.00% from 18 to 24, 31.60% from 25 to 44, 23.50% from 45 to 64, and 14.40% 65 or older. The median age was 38 years. For every 100 females, there were 91.40 males. For every 100 females age 18 and over, there were 87.60 males. The median household income was $63,432 and the median family income was $77,847 (these figures had risen to $77,294 and $95,243 respectively as of a 2007 estimate). Males had a median income of $51,301 versus $37,108 for females. The per capita income for the county was $32,484. About 2.90% of families and 4.60% of the population were below the poverty line, including 4.40% of those under age 18 and 5.70% of those age 65 or over. 2010 census As of the 2010 United States census, there were 670,850 people, 257,914 households, and 168,903 families residing in the county. The population density was . There were 270,359 housing units at an average density of . The racial makeup of the county was 82.3% white, 8.6% Asian, 5.7% black or African American, 0.2% American Indian, 1.3% from other races, and 1.9% from two or more races. Those of Hispanic or Latino origin made up 3.3% of the population. The largest ancestry groups were: 31.8% Irish 15.5% Italian 11.0% English 7.0% German 4.6% French 4.3% Chinese 4.1% Polish 3.2% Russian 3.1% American 2.8% Scottish 2.6% French Canadian 2.4% Scotch-Irish 2.0% West Indian 2.0% Sub-Saharan African 1.9% Portuguese 1.8% Swedish 1.6% Indian 1.4% Arab 1.4% Greek 1.2% Canadian 1.1% Vietnamese 1.1% Lithuanian Of the 257,914 households, 32.2% had children under the age of 18 living with them, 52.0% were married couples living together, 10.1% had a female householder with no husband present, 34.5% were non-families, and 27.6% of households were made up of individuals. The average household size was 2.53 and the average family size was 3.15. The median age was 40.7 years. The median income for a household in the county was $81,027 and the median family income was $101,870. Males had a median income of $68,070 versus $51,870 for females. The per capita income for the county was $42,371. About 4.1% of families and 6.2% of the population were below the poverty line, including 6.3% of those under age 18 and 6.9% of those age 65