Indiana saw another year of steep growth in its private school voucher program, with more than 29,000 students using the program to attend private school now estimated to be costing taxpayers more than $116 million.

That’s an increase in participation of nearly 50 percent during this past year.

Students using the voucher program — the second largest and fastest-growing of its kind in the nation — now account for 2.6 percent of Indiana’s school system, according to the latest annual report released Monday by the Indiana Department of Education.

Vouchers, billed by the state as “choice scholarships,” funnel tax dollars to support student tuition at private schools. The program is controversial: Proponents say the program expands quality options for poor children, and opponents say the state shouldn’t use tax dollars to pay for religious education while draining the coffers of public schools.

Hoosiers for Quality Education President Betsy Wiley, whose organization hosted a rally at the Statehouse last week supporting school choice, cheered the news.

“We are encouraged by this growth and what it means for families who want more options for their children, but there is still more to be done,” Wiley said. “Over 100,000 students are attending an underperforming school in our state. We believe we can do better. Parents must be provided with more high-quality school options.”

But the Indiana State Teachers Association said it was concerned about the growing rolls of students using vouchers who never previously attended a public school. This year roughly 50 percent of students using vouchers previously attended a public school; last year 61 percent of students did, stoking fears that the program is subsidizing private school tuition for families who already planned to do so.

“The voucher program was originally sold to Hoosiers as an alternative for low income families to use if their schools were failing,” ISTA President Teresa Meredith said. “The most expansive voucher program in America has become an entitlement program which in large part, now benefits middle class families who always intended to send their children to private (mostly religious) schools and taxpayers are footing the growing bill.”

Indiana’s voucher program has seen steep growth each year since it started in 2011-12 with nearly 4,000 students and 241 schools. It more than doubled in size the second year of the program to 9,000 students and continued that speed last year when it grew to nearly 20,000 students.

Several rules placed on the program at its infancy have since relaxed, including the enrollment cap in the first two years and a requirement that students must first try out a public school in their neighborhood before they used a scholarship. New rules last year also allowed siblings and students qualifying for special education services to use vouchers.

The program has also become less racially diverse over time. This year 61 percent of students using vouchers are white, compared with 46 percent when it started. Just 14 percent of the students are black this year, compared with 24 percent in 2011-12. (Overall, 71 percent of Indiana students are white. About 12 percent are black.)

The program’s use in suburban areas also is rising slightly, with 21 percent of voucher families living in suburban areas this year compared with just 16 percent three years ago.

(Correction: This story has been updated to reflect that Indiana no longer has the largest state voucher program. Wisconsin has a larger program as of December 2014.)