(CNN) There have been 957,892 arrests among children younger than 15 in the past five years in the United States, FBI statistics show.

The figure is based on the agency's annual crime reports in the US, including its latest 2018 numbers, released Monday.

In 2018, there were 1,324 arrests in that age group for rape, 7,415 arrests for aggravated assault and 20,058 arrests for larceny-theft, FBI data show.

The number of arrests of children under 15 has dropped consistently since 2014, the data show.

Violent crime in the US has dropped 2 years in a row

Violent crime across the country also declined for the second year in a row, the 2018 FBI statistics show.

The national violent crime rate fell 3.9% compared with the 2017 rate, according to the FBI. That includes murder and nonnegligent manslaughter offenses, which dropped by 6.2% compared with the 2017 numbers.

Rape offenses increased in 2018 by 2.7%, according to the data.

Property crimes also dropped 6.3% from the 2017, making this the 16th consecutive year those kinds of offenses are on the decline, the FBI said.

There were about 1,206,836 violent crimes in 2018 nationwide, the FBI said.

The Brennan Center for Justice called the new data "great news."

The data are "consistent with trends first observed in Brennan Center crime analyses studying America's largest cities," Ames Grawert, a senior counsel with the center, said.

"This downward national trend has lasted more than a quarter century," he said.

But the data also show crime rates in some cities "have not improved as quickly as we would hope," Grawert noted.

"Policymakers and advocates need to develop innovative solutions to help those cities share in the national trend toward greater safety. And these strategies must not be guided by the overly punitive approaches that helped drive mass incarceration across America," Grawert said in a statement.

Research by the Brennan Center showed some cities -- like Washington DC and Philadelphia -- saw their murder rates rise.