The first release from the Cambridge Police Department’s BridgeStat program — designed to share crime-fighting information with the public — tracks 40 years of data to reveal a marked decline in property crime and slight decline in violent crime.

Thanks to the dramatic drop in property crime, the total crime rate has a drop that is only slightly less dramatic.

The total crime rate is at its lowest level in more than 40 years, the document says.

The release can be seen by clicking here.

The peak year for property crime from 1970 to 2008 was in 1974, when 10,716 complaints were filed, according to the document. Two years ago, that figure had dwindled to 3,121, for a 68 percent drop.

The top year for violent crime over the past four decades was 1990, when there were 1,077 incidents reported. Last year, there were 449 — the second-lowest number in 40 years and a 58 percent drop, the document says.

BridgeStat is similar to the CitiStat data program used in New York City and those in use in other major cities including Los Angeles, Philadelphia, San Francisco, Baltimore, Washington, D.C., and Austin, Texas, said the department’s communication specialist, Dan Riviello.

Police use the data to devise strategies and tactics to solve problems and reduce crime, he said.

Crime is down 7 percent from last year, the document says. It also cites a year-to-year drop in a violent crime reports, by 17 percent, and property crime reports, by 6 percent.

The report goes into detail on specific types of crime by comparing this year’s statistics from January to June with statistics from last year for the same period, Riviello said. (It also looks at a weighted average from the past five years.)

Because the document didn’t say clearly that it was comparing similar periods from different years, Cambridge Day delayed writing about it until the methodology could be confirmed.

“We now realize that the presentation may be confusing,” Riviello said. “We will be sure to address this confusion in our next release.”

Comparing last year’s figures to this year, to date, police are seeing an increase in rapes — 16 this year compared with 14 last year — but warn that the numbers are preliminary. None of the rape accusations involve strangers.

More bicycles are being stolen as well, police said, with 148 taken so far this year. This was seen as a 54 percent increase in bike thefts, with Central Square cited as the most likely nonresidential area for thefts and Porter Square the least likely. “Larceny from person,” such as pickpocketing or purse theft, and “larceny from home” were also up slightly (in the latter case, by only 3 percent). There have been “numerous arrests” in the larceny categories, police assured.

Other kinds of crimes are all seen by police to be down, led by a 100 percent decrease in murders, since there were two last year and, so far, only one this year. Commercial robberies are estimated to be down 48 percent, with 10 this year compared with 14 in the same period last year. Street robberies were said to be down 35 percent; there have been 47 so far this year, which the document compares with 77 in the same period last year.

Future BridgeStat releases “will contain more comprehensive information broken down by neighborhood and business district, as well as detailed maps showing areas that are most susceptible to certain types of crime,” Riviello said in a press release.