Whether or not it’s due to any organized effort, the count through May does indicate the rate is down, thanks to a sharp fall in the number of robberies.

According to Police Department spokeswoman Kammie Michael, robberies are down by more than 15 percent year-to-date, compared with 2011. One reason could be that several people who have been arrested for multiple robberies in recent years are still in jail.

“For example, Raymond Parker and Alonzo Greene were arrested and charged with a dozen commercial armed robberies early last year,” Michael said.

“There may be several reasons for the decrease, but it is hard to say for sure because there are always cyclical ebbs and flows with crime,” Michael said.

Wanda Boone, head of the Durham TRY citizens’ anti-crime group, said she has been reviewing the data but, “I haven’t completed my thoughts.”

The robbery decrease stands out because the rate had been fairly consistent over the past few years. The rates of aggravated assault and homicide in the January-May period, on the other hand, have trended up.

According to preliminary figures compiled for Project Safe Neighborhoods (bit.ly/Lw2pOV), there were 325 gun-involved violent crimes within the city limits during the year’s first five months:

• nine homicides,

• 184 aggravated assaults,

• 132 robberies.

Through May 2011, the corresponding figures were:

• eight homicides,

• 177 aggravated assaults,

• 180 robberies,

for a total of 365 violent crimes involving guns.

The 2011 numbers were similar to those of 2010:

• 7 homicides,

• 184 aggravated assaults,

• 171 robberies,

for a total of 362; in 2009, there were 341 of the gun crimes Project Safe Neighborhood tracks:

• 4 homicides

• 161 aggravated assaults,

• 176 robberies.

In 2007, before current Police Chief Jose L. Lopez came to Durham, the January-May numbers were:

• 5 homicides,

• 152 aggravated assaults,

• 181 robberies.

Project Safe Neighborhoods compiles month-by-month statistics on gun crimes and arrests. Those are distributed to the Partners Against Crime citizens’ organizations in each of the city’s five police districts and posted on PSN’s website. Project Safe Neighborhoods is a Police Department program to involve residents and neighborhood organizations with professional law-enforcement agencies to reduce violent crime and make information available to the public.