Prostitution, indecent exposure and disorderly conduct charges also showed modest decreases.
Even though narcotics arrests decreased 17 percent from 146 to 120, the statistic does not necessarily represent a drop in drug usage.
"When evaluating statistics for drug arrests, it is important to keep in mind that the numbers reflect only arrests or complaints, and do not include all incidents of drug use in a particular area," the report reads.
Although the report shows no murders through September, the final tallies for the year will include two homicides from an Oct. 16 double murder. For the same nine-month period in 1997, two murders were recorded.
The report says the figure is consistent with the average yearly murder rate of 2.5 during the 1990s. In the 1980s, Cambridge had a murder rate of 4.5.
The CPD report says both figures are well below the national average of 10 for a city of comparable size.
CPD officials were not available for comment yesterday.