In Wisconsin, we'll use school attendance reports from the Department of Public Instruction for the 2013-14 school year, which are measured on the third Friday of September. Those also include kindergarten and 4-year-old kindergarten, unlike the Trulia analysis.

The Wisconsin figures show 959,831 students enrolled in school last year. The breakdown:

• 865,119 in a public district.

• 85,417 in a private school.

• 8,412 in one of 23 entities known as a 2R charter school, which instead of being run through a district is authorized by the Milwaukee common council, UW-Milwaukee or UW-Parkside.

• 883 students enrolled with the Department of Corrections or Department of Health Services.

That means in Wisconsin, 8.9 percent of students were enrolled in a private school last year.

We wanted to look closer at where those students are concentrated, so we'll use a DPI breakdown of private-school enrollment by the public district in which the private school is located.