The past year and a half have seen a parade of monthly headlines about gun-sales records being broken—and September proved no different.

According to FBI statistics released on Monday, last month saw the largest number of sales of any September on record—totalling nearly 2 million—and marked the 17th straight month of record-breaking background-check numbers.

As usual, these numbers come from the FBI-run National Instant Criminal Background Check System (NICS), which tracks the number of background check requests it processes.

Exactly 1,992,219 NICS checks were performed in September, bringing the running total for 2016 to a staggering 19.8 million, with four months left in the year, as Fox News reports. The September totals represent and increase of nearly 200,000 checks, about 10 percent, over September 2015.

The number isn’t a direct corollary to the number of guns sold, since the NICS numbers don’t reflect the number of background checks denied by the FBI. Also, one check can be performed for multiple gun purchases, and NICS background checks are used for purposes other than firearms purchases. But the numbers are a good indicator of guns sales, since a NICS check must be performed by every licensed gun dealer for every firearm sale in every state. Some states require NICS checks for private sales as well.

“These statistics represent the number of firearm background checks initiated through the NICS,” a note from the FBI said. “They do not represent the number of firearms sold. Based on varying state laws and purchase scenarios, a one-to-one correlation cannot be made between firearm background checks and firearms sale.”