When convicted murderers David Sweat and Richard Matt escaped from a New York prison over the weekend, the state’s governor said everyone should be worried.

“This is a crisis situation for the state,” New York Gov. Andrew M. Cuomo (D) said, as the Associated Press reported. “These are dangerous men capable of committing grave crimes again.”

But while the means of escape — power tools, steam pipes and manhole covers — were dramatic and the men who employed them highly dangerous, prisoner escapes are an everyday occurrence in the United States. Bureau of Justice Statistics (BJS) data from 2013, the most recent year available, noted 2,001 counts of “AWOL/escape” among prisoners serving sentences of more than one year, including 22 in New York alone.

That year was an outlier — because it was an improvement. More than 2,500 escaped in 2010; more than 3,100 escaped in 2011; and more than 2,500 escaped in 2012. Indeed, prisoner escapes dwindled in the past two decades even as the prison population rose. In 2013, the U.S. prison population was about 1.5 million. But in 1993, 14,305 prisoners escaped out of a prison population of 780,357 — that’s 2 percent of the entire prison population on the lam, as Slate pointed out.

When someone is sent up the river, the assumption is that he or she stays there. So why all the escapes?

“In the US, despite an unprecedented level of modern prison construction in the closing decades of the 20th century and the development of increasingly sophisticated security technology, prison escapes are seemingly inexorable,” Elizabeth Bracco and Richard F. Culp wrote in an academic paper published in Corrections Compendium in 2005. “In a correctional setting populated with potential escapees, dependent upon sophisticated and functioning security technology and staffed by rotating shifts of correctional officers of varying levels of skill and experience, the possibility of escapes is omnipresent.”

Most escapes don’t evoke comparisons to “The Shawshank Redemption,” as New York’s did this past weekend. Many are as simple as an inmate not showing up.

“The vast majority of escapees are ‘walk-aways’ from community corrections facilities that have minimal supervision,” Slate reported in 2001. “Dramatic, Hollywood-style escapes from maximum security prisons are the ones that draw media attention. Like their maximum security counterparts, the minimum security walk-aways are usually recovered.”

Escapes from the kind of prisons with walls are much fewer.

“This is really unusual,” Keramet Reiter, an assistant professor of criminology at University of California at Irvine, said after a prison escape in Michigan last year. “It’s incredibly rare with a prison that has perimeter security.”

The feds are also lot better at holding on to its prisoners than states. In 2013, for example, federal facilities were responsible for exactly 0 percent of AWOL/escapes, according to the BJS statistics.

Still, though the feds may be blameless, counting prison breaks is complicated. The BJS, for example, doesn’t differentiate between Clint Eastwood/Steve McQueen-style great escapes and a guy who doesn’t get back to a halfway house on time because he missed a bus. Prisoners can even “escape” by being released too early because of sentence calculation errors. This makes it hard to determine how common actual escapes are.

Even reports of this past weekend’s escapes seemed a bit confused. Officials told the New York Times the last New York state prison break occurred in 2003; yet, the state itself reported one of its prisoners escaped from a medical facility in 2005.

In addition, the BJS counts incidents of “AWOL/escape” only among prisoners serving more than one year, which may understate the problem. In 2012, for example, the New York Times reported 1,300 inmates had walked away from New Jersey halfway houses since Gov. Chris Christie (R) took office. In the same period, the BJS recorded less than 200 counts of AWOL/escape.

No matter how frequent prison escapes are, it’s clear they’re not going away soon. One great mind even said eliminating escapes was impossible.

“As a general rule, it can safely be assumed that cemeteries are the only places which effectively ensure the non-recurrence of escapes,” British criminologist Sir Leon Radzinowicz, who helped define the field in the 20th century, wrote in “Adventures in Criminology” in 1999. “… It is therefore unsound to examine prison escapes in absolute terms and it is much more realistic to talk about ‘tolerable escape rates.'”

Here’s a look at the 2013 BJS data:

Counts of “AWOL/escape” in 2013 (based on prisoners with a sentence of more than one year)

National Statistics (U.S. Total) 2001
Federal Institutions 0
State Institutions (Total) 2001
Alabama 687
Alaska 0
Arizona 0
Arkansas 0
California 0
Colorado 13
Connecticut 199
Delaware 7
District of Columbia 0
Florida 0
Georgia 0
Hawaii 0
Idaho 1
Illinois 56
Indiana 115
Iowa 246
Kansas 19
Kentucky 61
Louisiana 104
Maine 0
Maryland 29
Massachusetts 3
Michigan 0
Minnesota 0
Mississippi 1
Missouri 0
Montana 0
Nebraska 30
Nevada 1
New Hampshire 6
New Jersey 180
New Mexico 2
New York 22
North Carolina 0
North Dakota 14
Ohio 3
Oklahoma 1
Oregon 9
Pennsylvania 82
Rhode Island 1
South Carolina 7
South Dakota 17
Tennessee 3
Texas 0
Utah 0
Vermont 0
Virginia 11
Washington 42
West Virginia 14
Wisconsin 7
Wyoming 8

SOURCE: Bureau of Justice Statistics/National Prisoner Statistics/E. Ann Carson and Joseph Mulako-Wangota.