Chicago Police officers made 85,493 arrests in 2016, a 24 percent drop from the year before and roughly half the number of arrests they made the year before Mayor Rahm Emanuel took office.

The steady and precipitous decline in arrests coincided with the mayor’s decision to rely on overtime — to the tune of $143 million last year, and even more during in the first quarter of this year — to mask a severe manpower shortage before abruptly reversing course and embarking on a two-year hiring blitz.

The decline also underscored how important it is for Emanuel to bolster police morale and coax police officers out of their defensive crouch.

The arrest figures are a buried treasure included in the city’s Comprehensive Annual Financial Report for 2016.

They show that Chicago Police officers made 167,355 arrests in 2010; 152,740 in 2011; 145,390 in 2012; 143,618 in 2013; 129,166 in 2014; 112,996 in 2015, and 85,493 last year.

The largest percentage drop occurred between 2015, when a judge ordered the city to release the Laquan McDonald shooting video, and 2016, when the U.S. Justice Department conducted its sweeping civil rights investigation of the Chicago Police Department triggered by the shooting of the black teenager.

Fraternal Order of Police President Kevin Graham said the “steady and striking” decline in police arrests cannot be explained away by the fear police officers have of being captured on the next YouTube video.

“One problem is that our members are being excessively punished for minor or insignificant infractions. More importantly, there is a growing body of evidence that our officers are unfairly vilified, even when they conduct themselves ethically and according to the law and city policy,” Graham wrote in an emailed statement.

“The vilification of the police has been raised to a kind of hysteria, bolstered by the media, which, to this day, refuses to acknowledge the evidence of corruption in the anti-police movement,” he wrote. “Instead, the media prefer to rely on tired and false clichés about ‘a code of silence’ among our members, rather than reasonably following and weighing the evidence.”

Ald. Anthony Beale (9th), former longtime chairman of the City Council’s Police Committee, accused Chicago Police officers of abandoning pro-active policing.

“I can ride around and show you things police tolerate in our community that they don’t tolerate in other communities. They just drive right past. Quality of life issues are not being enforced in communities of color,” Beale said.

“Guys hanging out on the corner shooting crap. A group of guys on the corner drinking. People having parties that get out of hand,” he said. “A lot of your drive-by shootings are people hanging out on corners. That’s an opportunity. If we police quality of life issues, we take away the opportunity.”

Chicago Police Department spokesman Anthony Guglielmi acknowledged that “last year’s results across the board were not acceptable to anyone — especially CPD.” He was referring to a homicide rate not seen since the 1990s.

But Guglielmi argued that a “mass arrest strategy is not the solution, either.”

“CPD has implemented a strategy shift to arrest the right people for the right reasons. Our efforts focus enforcement around the disproportionate number of violent offenders, most of whom are documented gang members, and pose the greatest risk to our neighborhoods,” Guglielmi wrote in an email to the Chicago Sun-Times.

“CPD is also working to find alternatives for nonviolent drug offenders in lieu of being charged with a crime. … We have begun implementing programs to divert nonviolent drug offenders into treatment programs instead of incarceration,” he wrote. “Ultimately, increasing arrest numbers is not our goal, it’s reducing crime numbers.”

In the fall of 2015, Emanuel contended during a closed-door meeting with then-Attorney General Loretta Lynch and 20 big-city mayors and police chiefs that police officers across the nation were becoming “fetal” because they’re afraid their videotaped encounters with the public will end up on YouTube.

Less than two months later, the pullback by Chicago Police officers got dramatically worse. It happened after the court-ordered release of the video showing white police officer Jason Van Dyke shooting black teenager Laquan McDonald 16 times.

“You have these body cameras now. The spotlight is on `em. So, they’re taking a more passive approach. They’re protecting themselves moreso than they’re protecting the communities,” Beale said on Monday.

After disclosing plans to hire 970 additional police officers over a two-year period above attrition, Emanuel openly acknowledged that it won’t matter how many new officers the city hires if cops are in a defensive crouch.

“We can’t have a Police Department that feels like it’s better for them to just drive in a community without stopping and stopping the gangbangers and the drug dealers. That’s not good and healthy for the community,” the mayor said then.

“Unless we change the narrative where our police are seen as being put on the defensive, we’re not gonna get where we need to be,” the mayor said.

ACLU spokesman Ed Yohnka maintained on Monday that the drop in police arrests could be a simple reflection of “giving a lower priority to making arrests for small amounts of marijuana.”

“It is not how many arrests are being made, it is that the right arrests are being made for the right reasons are being made,” Yohnka wrote in an email. “As for the argument of a Ferguson effect, we reject that notion [as has the former Attorney General Eric Holder and former President Barack Obama.] Good policing — keeping communities free of gun fire and open air drug markets — and community policing are not inconsistent.”

In January, the Chicago Police Department and the ACLU once again agreed to simplify a burdensome “investigatory stop report.”

But the police union argued then that the changes would not be enough to reverse an 80 percent drop in street stops.

On Monday, Yohnka noted that the Sun-Times has reported extensively on “what happens when police operate in an uncontrolled fashion: we end up with arrests where the charges are not sustained. We need smart policing that serves the entire community, not simply larger numbers on a spreadsheet.”