Ann Arbor, Michigan:

In 2000, out of 45,693 households, 23.0% had children under the age of 18 living with them, 37.8% were married couples living together, 7.5% had a female householder with no husband present, and 52.5% were nonfamilies. 35.5% of households were made up of individuals and 6.6% had someone living alone who was 65 years of age or older. The average household size was 2.22 and the average family size was 2.90. The age distribution was 16.8% under 18, 26.8% from 18 to 24, 31.2% from 25 to 44, 17.3% from 45 to 64, and 7.9% were 65 or older. The median age was 28 years. For every 100 females there were 97.7 males; while for every 100 females age 18 and over, there were 96.4 males.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". In what year was the average family size was 2.22?
unanswerable