More than 700,000 foreign nationals who were supposed to leave the U.S. in recent months overstayed their visas, the Department of Homeland Security said in a report released Tuesday.

The federal department determined that 701,900 people who entered the country through an air or sea Port of Entry overstayed their visas between October 2016 and September 2017.

Overall, an estimated 40 percent of the roughly 11 million people in the country illegally stayed past their visas.

The total number of overstays is much larger but has not been quantified because it doesn't include how many people arrive by land.

The 2016 overstay report — the first one published by Homeland Security in at least two decades — stated 739,478 people who entered the U.S. via plane or ship overstayed their visas between October 2015 and September 2016.

Overstays accounted for 1.3 percent of the 52.7 million visitors who arrived by plane or ship during the latest period, an improvement from the overstay rate of 1.5 percent a year earlier.

Canada again occupied the top slot for overstays, followed by Mexico, Venezuela, the United Kingdom and Colombia. Nigeria, China, France, Spain and Germany rounded out the top 10.

The overstay rate was much higher among students and foreign exchange visitors, with 4.2 percent staying after their visas expired, a decline from 5.5 percent the previous year.

The Associated Press contributed to this report.