The number of juveniles jailed across New Jersey in the last eight years declined significantly, saving the state millions of dollars, according to a report released Wednesday by a nonprofit children's public policy and advocacy group.

The Kids Count Special Report compares the number of juveniles jailed in 2011 to 2004, when five counties joined a national initiative offering alternatives to detention. The report showed a 60 percent decrease, partly from using electronic monitoring and reporting mandates.

Detention costs $136,000 a year per youth; the 60 percent decrease has saved $16 million a year, according to the report.

"For years, New Jersey locked up thousands of juveniles, often for minor, nonviolent crimes, warehousing them in overcrowded, unsafe detention centers," said Cecilia Zalkind, executive director of Advocates for Children of New Jersey, which released the report.

"Today, we have a completely different system that safely keeps most youth out of lockup and works to put these children on a path to productive adulthood," she said.

According to the report, youth who are detained are more likely to commit another crime, more likely to have trouble in school, and will likely face more difficulty finding a job. It also says juvenile detention does not improve public safety.

Alternative supervision included electronic and in-home monitoring systems, or mandatory reporting to day and evening centers. Job training, mentoring to address the issues that led to criminal behavior, and support to meet probation conditions also were provided.

The report focuses on participating counties that used a $200,000 grant from the Annie E. Casey Foundation, which advocates youth reforms.

In New Jersey, 16 of the state's 21 counties are now participating the Juvenile Detention Alternatives Initiative. Gloucester County was the last to join last year, closing its juvenile detention facility and consolidating services with Camden County, officials said.

Camden and Burlington Counties showed significant decreases in detention. Camden, among the first counties to participate, had 1,679 detentions in 2004 compared to 388 in 2011 - a 77 percent decrease. Burlington joined the initiative in 2006, dropping detentions 52 percent from 284 to 137.

Burlington County Prosecutor Robert D. Bernardi said his office filters out nonviolent juveniles.

"We will continue to work toward that goal, while at the same time making sure that the public is protected," Bernardi said.

Admissions from 15 counties show the number of youthful offenders detained dropped 60 percent, from 10,191 to 4,093 last year.

"This report chronicles important, positive change as a result of New Jersey's commitment to juvenile detention reform," Attorney General Jeffrey S. Chiesa said in a statement. "In New Jersey, many individuals and agencies have worked together successfully to establish a fair and consistent approach to juvenile justice."

The report notes that although juvenile arrests for serious offenses dropped 45 percent from 1993 to 2002, the average daily detention population increased by 38 percent.

"This has resulted in a juvenile justice system that is smarter, safer, and saving taxpayer dollars," Zalkind said. "The success of the detention alternatives initiative should be used to inform and guide future juvenile justice reforms."