The monthly population of the youth secure estate is based on the number of young people in custody at the beginning of the month, plus new admissions during the month. This is then averaged over the year and used to calculate the rate of assaults.
Figures do not include data where ethnicity is unknown.
Rates per 100 young people in custody are rounded to the nearest whole number. You can see rates rounded to 1 decimal place if you download the data.