3.65% of the population. 23.8% were of German , 10.6% English , 10.1% Irish and 7.1% American ancestry according to Census 2000 . 91.0% spoke English , 2.9% Spanish and 1.0% Chinese or Mandarin as their first language. Of the 31,388 households, 25.1% included children under the age of 18, 38.0%