The extent of youthful crime is hard to judge. Since the Second World War, a substantial increase in juvenile convictions has been recorded in many countries. As offenders, boys outnumber girls in a ratio of about 10 to 1. Juvenile delinquency rates may rise with a higher general technological economic level and in situations of varied social change. Hence western Europe, USA and Japan have high levels of juvenile delinquency. Youth gangs are noted also in Taiwan, South Africa, Australia, New Zealand, Poland, USSR and Yugoslavia. Juvenile delinquency has shown a sharp increase in such rapidly developing nations as Ghana and Kenya. Crimes against property are by far the most frequent type of offence. These include stealing from shops, houses, and cars; and the unauthorized taking of cars, usually for joy-riding. Theft seems to be associated more with the younger offender. Crimes against the person (assaults, fighting, robbery with violence), together with sex offences and, in industrially developed countries, traffic offences, come next and are more common among those aged from 17 to 21. Narcotic addiction and other types of drug dependence, though not always criminal offences, are a relatively new and disturbing form of deviance and seem to be increasing rapidly.
The 1991 UK National Prisons Survey found 38 percent of lock-up young offenders had been in council care, against 2 percent of the population as a whole. In 1992 in Britain, 110,4000 children aged 10-16 were caught breaking the law; 75 percent were boys. By far the most common crime was theft or handling stolen goods. In 1993, nearly two-thirds of British teenagers knew someone in their age group who breaks the law. Under-age drinking and shoplifting were the most common offences, followed by truancy, taking drugs, vandalism, bullying and joyriding. Over half cited "to impress others" and boredom as the reason for offending, followed by lack of money, peer pressure, lack of parental strictness and ability to get away with it.