During the first half of this period, the number of juvenile delinquents rose, but then decreased after 1965. Only the number of traffic and minor offenders rose in the 1970's. Serious offenders who committed rapes, murders, arson, and assault decreased rapidly and numbered about half of that in 1955. However, the number of drug abusers has increased since 1975. During this period, the rate of dismissal before hearing in family court increased, while those of probation and commitment to juvenile institutions dramatically decreased, particularly between 1955 and 1975. Beginning in 1977, Japan started to implement reforms in treatment measures for juvenile traffic and non-traffic offenders. These reforms occurred in juvenile probation and training schools. As a result, courts have begun to send more offenders to short-term treatment programs at juvenile schools, while a greater proportion of less serious offenders has been assigned to probation. 1 table