Registered crimes are crimes that are reported by the victim or by the police. The share of registered crimes in summer is determined by dividing the number of offences committed in the months of July and August by the annual total. This may vary between 0 and 100 percent. In case of an equal distribution of offences over the year, the share of summer amounts to 16.7 percent, i.e. two out of the twelve months. If all crimes are committed in summer, the summer peak is at its highest (100 percent).
For this research on seasonal criminal activity, crime types have been selected where reporting by the victim is customary. The following four main categories are taken as a basis:
1) High-impact property offences
2) Minor property offences
3) Violent and sexual offences
4) Vandalism and offences against public order