DENVER -- The number of serious crimes reported in the Denver metro area has increased significantly for the first time in nearly a decade.

Serious crimes are up twelve percent, according to preliminary statistics.

The recent numbers come from 13 area law enforcement agencies, incorporating eight categories of crime including homicide, rape, robbery, aggravated assault, burglary, theft, auto theft and arson.

The statistics were requested by the Rocky Mountain News, and provided by sheriff's offices in Boulder, Jefferson, Arapahoe, Adams and Douglas counties and police departments in Arvada, Aurora, Boulder, Castle Rock, Denver, Lakewood, Littleton and Thornton.

Overall, Adams County has the highest increase in reported crimes at 17 percent.

Arapahoe County saw a 14 percent rise, Arvada a 10 percent jump and Aurora had a 9 percent spike.

Boulder is near the top of the list with a 16 percent increase. Denver's was at 14 percent, Douglas county at 11 percent and Lakewood at 13 percent.

The only counties or cities polled that had overall decreases were Castle Rock, Jefferson County and Littleton.

The increase in crime, after declines for eight years and then a leveling off last year, seemed to match forecaster's predictions for a changing population, said Joseph Sandoval, chairman of the department of criminal justice and criminology at Metropolitan State College in Denver.

"They expected there to be an increase in the number of folks hitting that age when most people commit crimes," Sandoval said. He said most crimes are committed by offenders in their late teens to late 20s.

Property crimes accounted for the bulk of the increase in reports, with robberies jumping 15 percent last year, theft increasing 11 percent and burglary climbing 7 percent.

According to theNews, the numbers are gathered for use in the crime index the FBI puts together about cities throughout the nation.