San Francisco has by far the highest property crime rate in California, with more than twice the number of reported thefts per capita than Los Angeles or Santa Clara counties, according to a new report by the Public Policy Institute of California.

And when it comes to arrests, San Francisco is 50th out of the state’s 58 counties.

Statewide police records reviewed by the PPIC show San Francisco averaged a whopping 5,844 property crimes per 100,000 residents per year from 2014 to 2016, the last period for which detailed arrest data are available. Alameda County, which includes Oakland, came in second statewide with 3,666 crimes per 100,000 residents.

Los Angeles County, by comparison, was at 25th, reporting an average of 2,398 crimes per 100,000 residents. Santa Clara County, which includes San Jose, came in 30th, with an average of 2,282 per 100,000 residents — less than half the property crime rate of San Francisco.

“One contributing factor is the high number of larcenies, which include auto break-ins, theft and burglaries,” said PPIC analyst Magnus Lofstrom. “It’s very hard to catch someone committing a car burglary. It happens very fast.”

Property crime includes burglary, motor vehicle theft and larcenies such as pickpocketing and shoplifting.

As for arrests, San Francisco clocked in with 226 property-crime annual arrests per 100,000 residents over the two-year period compared with Alameda County’s 374 per 100,000 residents, Los Angeles County’s 371 and Santa Clara County’s 283.

San Francisco also had the distinction of the highest per-capita property-crime rate among the 20 biggest U.S. cities in 2017, FBI data show.

Lofstrom said San Francisco’s daily influx of tourists and commuters leads to higher crime rates — more visitors, more victims.

“Crime rates are calculated based on reported crimes per 100,000 residents, but tourists and commuters are not counted as residents,” Magnus said.

San Francisco police contend, however, that the situation is improving.

“The data cited in the PPIC report is 3 to 5 years old,” said San Francisco police spokesman David Stevenson, who added that the city has doubled foot patrols to deter street crimes and assigned plainclothes officers to focus on vehicle burglaries and other street crimes.

The added police effort helped reduce auto burglaries by 13% from 2017 to 2018. As of the end of July this year, auto burglaries were down 10% from 2018. Property crimes are down 9% year to date, according to San Francisco Police Department records.

“As the report notes, many of these are crimes of opportunity, such as auto break-ins, in which a small crew of suspects can commit several break-ins and get away quickly,” Stevenson said. “Nevertheless, we are making arrests.”

Still, according to The Chronicle’s Car Break-in Tracker, there were 2,279 vehicle break-ins reported in San Francisco last month, or roughly 73 per day.

One contributing factor to the plague of property crimes statewide appears to be the aftereffect of Proposition 47, a voter-approved measure that dropped property crimes of less than $950 in value to a misdemeanor that carries little if any jail time.

Prop. 47 was part of former Gov. Jerry Brown’s criminal justice reforms intended to reduce the state’s overcrowded prison system, which at the same time offered nonviolent petty offenders alternatives to jail time.

“We have to work within the parameters of the laws that are passed by legislators or voted on by the public,” Stevenson said. “As always, our focus is on public safety, deterring crime and building strong cases for prosecution and justice in our courts.”

That, Lofstrom concluded, may have led to fewer arrests.

“It is plausible that, faced with crowded jail facilities, law enforcement officers may have reduced arrests, especially for lower-level offenses, since they may have expected some suspects to be released shortly after being booked into jail,” Lofstrom wrote in the report. “There is a lower likelihood of consequences for committing lower-level, or misdemeanor, crimes.”

Where candidates’ stand

In light of the PPIC report we asked the four candidates for San Francisco district attorney if they thought Prop. 47 was working?

Their responses:

Chesa Boudin: “Prop. 47 is working. It has reduced California’s prison and jail populations by more than 20,000 and provided $100 million for treatment and rehabilitation programs that will help break the cycle of crime. All this while still empowering district attorneys to effectively prosecute drug sales, auto burglaries and serious felonies.”

Leif Dautch: “The issue with Prop. 47 is not the law itself but the local implementation by San Francisco officials, including the district attorney. Importantly, crimes like car break-ins don’t fall under Prop. 47 and can still be prosecuted as felonies. So the lack of enforcement for these break-ins is a conscious choice by the D.A.’s office, not a limitation in existing law.”

Suzy Loftus: “Prop. 47 was about reducing wasted prison space on nonviolent crimes. That makes sense. It’s been up to local officials to solve nonviolent crimes without relying on costly and ineffective prison beds. Some counties have created new public safety strategies that work better. Others have failed to implement Prop. 47 effectively, and that’s about inadequate local leadership, not state law.”

Nancy Tung: “Prop. 47 reduced penalties for some crimes, like drug possession and theft, but the district attorney and police need to do a better job and use all available tools to protect our city. We can’t just throw up our hands and do nothing when what’s happening on our streets isn’t working.”

San Francisco Chronicle columnist Phil Matier appears Sundays and Wednesdays. Matier can be seen on the KPIX-TV morning and evening news. He can also be heard on KCBS radio Monday through Friday at 7:50 a.m. and 5:50 p.m. Got a tip? Call 415-777-8815, or email pmatier@sfchronicle.com Twitter: @philmatier