Answer based on context:

There were 19,707 households of which 31.0% had children under the age of 18 living with them, 51.6% were Marriage living together, 10.0% had a female householder with no husband present, 4.2% had a male householder with no wife present, and 34.2% were non-families. 28.2% of all households were made up of individuals and 10.1% had someone living alone who was 65 years of age or older. The average household size was 2.42 and the average family size was 2.97.

How many percent are not Marriage couples living together?
48.4