There were nearly 7.2 million complaints about violations to the U.S. “Do Not Call” registry this year, a big surge from the more than 5.3 million complaints in 2016.

The figure is almost double the nearly 3.6 million complaints in 2015.

New Jersey had the highest density of complaints on the “do not call” registry in 2017, according to new data released by the Federal Trade Commission on Monday.

For every 100,000 New Jersey residents, there were almost 3,600 complaints about spam calls, the FTC said. Delaware, Florida, Virginia and New Hampshire followed close behind with over 2,700 complaints per 100,000 residents. New Jersey and New Hampshire residents were also among the most likely to be on the “do not call” list.

Alaska, Hawaii, Missouri and North Dakota were relatively spam-free this year, the report said, with fewer than 1,400 complaints per 100,000 residents.

Robocalls were the worst offenders, and the most common topic, by far, was reducing debt. Other popular spam call topics were for timeshares, warranties and medical-related calls, according to the FTC. July and August appeared to be the peak time for spam calls.

The deluge could subside soon: Earlier this year, the Federal Communications Commission gave phone companies more power to block robocalls.

Here’s a full breakdown of state rankings by the FTC and some tips on how to cut down on spam callers:

Most “do not call” list violation complaints per 100,000 residents (source FTC)