(USA TODAY) - The Transportation Security Administration found 1,828 guns among travelers preparing to board planes in 2013, a 20% increase from the year before, according to an academic study.

The number of detections at airport checkpoints continues to rise from 1,123 in 2010 to 1,320 in 2011 to 1,525 last year, according to the tabulation of TSA data by Northwestern University's Medill National Security Journalism Initiative. About five guns are found every day nationwide.

About 84% of the weapons found were loaded and one in three had a bullet in the chamber ready to fire, according to the study. The most popular weapons found were .380-caliber and 9 mm handguns.

Five airports where the most firearms were found were: Atlanta with 110, Dallas-Fort Worth with 98, Houston with 67, Phoenix with 65 and Denver with 52, according to the study.

The TSA blog, which provided the information that the Medill analysis is based on, illustrated how many guns are found with the year's final installment. For the week ending Dec. 27, TSA found 31 firearms, with 25 loaded and seven with rounds in the firing chamber, according to the blog.

Federal regulations prohibit carrying guns in a plane's cabin.

TSA doesn't make arrests when guns are found at a checkpoint, but refers the traveler to local law enforcement officers. Depending on local laws, the passenger could be arrested, given a ticket or allowed to store the gun elsewhere.