The popularity of Confederate flag license plates in Tennessee has hit a 10-year high, according to data from the state’s department of revenue.

There were almost 3,300 active Sons of Confederate Veterans plates in Tennessee at the end of June, the Nashville Tennessean reports. While that’s a small number overall — Tennessee has a population of around 6.7 million, and more than 5.6 million passenger license plates in circulation — it represents a 72% increase over the end of fiscal year 2015, the year debates about the Confederate flag broke out in earnest, according to the newspaper.

Some proceeds from sales of the plate, which has the Confederate flag on the left side, benefit the Tennessee chapter of the Sons of Confederate Veterans, a Confederate pride non-profit. The vanity plate has been issued since 2004 and comes with an annual fee of $61.50. The Sons of Confederate Veterans earned almost $58,000 from the plates in fiscal year 2018, the Tennessean reports.

Tennessee Department of Revenue

The debate over Confederate flags and monuments intensified in 2015, when Dylann Roof, a white man, killed nine black worshippers in a South Carolina church. Roof, who was convicted of 33 counts of murder, attempted murder and hate crimes in 2016, was an avowed white supremacist and had posted photos online of himself posing with Confederate memorabilia.

Since the shooting, a number of Southern cities have removed Confederate monuments and statues, in some cases sparking backlash and protests from supporters.

A representative from the Sons of Confederate Veterans could not immediately be reached for comment by TIME, but told the Tennessean that the spike in its plate’s popularity likely stems from what the groups believes to be attacks on Confederate history.

“Every time that some of our history that we’re so proud of has been attacked, people have gone out, and probably some members who had license plates but quit renewing have gone back and put them back on their vehicle,” Division Commander James Patterson told the newspaper.

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Write to Jamie Ducharme at jamie.ducharme@time.com.