MADISON, Wis. — The vast majority of students receiving a taxpayer-subsidized voucher to attend private school this year did not go to a Wisconsin public school last year, according to data released Thursday by the state Department of Public Instruction.

Just over 19 percent of the 538 students who entered the statewide program this year attended a public school last year, the data showed. Over the two years of the program, just under 20 percent of those receiving a voucher came from a public school.

The voucher program is touted by supporters as a way to help students escape poorly performing public schools. But the latest numbers show most students were already in private school before they got the voucher, fueling arguments from opponents that the program is really about subsidizing private school education.

The head of the pro-voucher group School Choice Wisconsin said the numbers don’t tell the whole story. Most of the students in private school who accepted a voucher were receiving needs-based scholarships, School Choice Wisconsin president Jim Bender said. When they move into the voucher program, it opens up the scholarships for others in public school, he said.

Bender said he did not have an exact figure for many students who took a voucher had been on a scholarship.

To qualify for a voucher, a single parent with three children can earn up to $44,177 per year. For a married couple with two children, the cutoff is $51,177 annually. Once in the program, families no longer need to meet the income requirements.

The vouchers are worth $7,210 for students in elementary school and $7,856 for those in high school.

DPI’s numbers showed that 73 percent of new enrollees this year came from a private school. Just over 19 percent had been in a public school, and the rest were not in school, home-schooled or came from out of state.

Enrollment in the program is currently capped at 1,000 students. Gov. Scott Walker is campaigning on the promise that he will expand it, while Democratic challenger Mary Burke wants to do away with vouchers outside of Milwaukee and Racine, where they have been in place longer.