The number of police officers in Canada continues to rise despite a declining crime rate, with some forces now overstaffed, a new report from the Fraser Institute says.

As municipalities struggle with rising costs, officials should look at the nature and volume of police calls when talking to local unions about staffing levels, author Livio Di Matteo said.

The report looks at the number of police officers per 100,000 citizens as well as crime rates and other socioeconomic differences. The forces were then ranked based on efficiency.

Kelowna, B.C., Moncton, N.B., and Ottawa-Gatineau had the most efficient staffing levels, the report says.

Saint John, N.B., Winnipeg and Windsor, Ont., had the least efficient staffing levels.

The report notes between 2001 and 2012, police officers per 100,000 of population in Canada rose 8.7% while the crime rate decreased by 26.3%. This was coupled with an increase in expenditures, such as salary and resources, and a decrease in workload for officers.

"While more police can lead to lower crime rates, at some point, increased spending on additional police officers has little impact on crime reduction," Di Matteo said in a press release about the report.

"Of course, declining crime rates are a good thing, and some may attribute those declining rates to an increase in police spending. But in reality, some Canadian districts maintain substantially larger police forces than their crime rates warrant while other districts maintain smaller forces despite relatively high rates of crime."

In a statement after the report was released, Windsor Police Chief Al Frederick said the report "in no way accurately reflects the 2014 staffing levels" of his force. Between 2011 and this month, the Windsor force reduced its number of officers from 466 to 440.

Windsor Police receives full funding from the province for 21 officers to cover the casino in the city, and its lower drinking age than that in neighbouring Michigan means more officers are needed in the downtown, where there is a "concentrated number of liquor licence establishments."