Residents of two states voted to legalize marijuana in 2012, but despite an increase in public support for liberalizing drug policy, American police arrested about the same number of people last year on pot-related charges as in 2011.

Data released Monday by the Federal Bureau of Investigation show there were an estimated 1,552,432 arrests for drug-related crimes in 2012 – a slight uptick from the 1,531,251 drug arrests in 2011. Marijuana offenses accounted for 48.3 percent of all drug arrests, a slight reduction from 49.5 percent in 2011, which itself was the highest rate since before 1995.

Most marijuana-related arrests were for possession of the drug. By mere possession, there was one marijuana arrest every 48 seconds in 2012. Including arrests for distribution, there was a pot-related arrest every 42 seconds, the same interval as in 2011.

Advocacy groups that back campaigns to legalize or decriminalize weed said police should prioritize solving violent crimes – the number of which bumped upward from 2011 to 2012 – over arresting marijuana users.

According to the FBI's Uniform Crime Report data, there were an estimated 1,214,462 violent crimes reported to police in 2012, a 0.7 percent increase. FBI Director James Comey noted in a statement this was the first overall increase in violent crime in six years.

Just 40.1 percent of the 84,376 forcible rapes reported to police and 28.1 percent of the 354,520 robberies were solved by law enforcement. Around 62.5 percent of the 14,827 murder cases were closed, as were 55.8 percent of the 760,739 aggravated assaults.

"As a former prosecuting attorney myself, I believe it is irresponsible to squander our limited law enforcement resources on this disastrous public policy failure," said Dan Riffle, Marijuana Policy Project federal policies director, in a statement. "That is especially true when so many violent crimes remain unsolved. Every second spent arresting and prosecuting adults for marijuana is time that could have been spent preventing and solving real crimes."

The group Law Enforcement Against Prohibition, made up of former and current law-enforcers who want to dampen drug prohibition, said the same.

"Each one of those arrests is the story of someone who may suffer a variety of adverse effects from their interaction with the justice system," said LEAP Executive Director Neill Franklin, a former Maryland policeman, in a statement. "Commit a murder or a robbery and the government will still give you a student loan. Get convicted for smoking a joint and you're likely to lose it."

A poll released in April by the Pew Research Center found 52 percent of American adults believe marijuana should be legal.

It's possible the national arrest tally for marijuana will be lower in 2013. State and local police enforce most anti-pot laws, and Washington and Colorado residents, who make up around 4 percent of the total U.S. population, will enjoy a largely arrest-free year.

The FBI report said there were 12,196,959 arrests for any reason in 2012, around one every two seconds.