The paragraph is followed by an incomplete phrase or sentence which summarizes the main idea of the paragraph. Choose the missing words of the phrase or sentence. 

In the U.S. today, it is common to pay one fourth to one third of family’s income on the place to live. Big houses are more expensive than smaller ones. And houses closer to the center of big cities are more expensive than the ones in the suburbs or in small towns.
The （） of housing in the U.S. today is very high.