incidence
noun [ C usually singular ] formal uk/ˈɪn.sɪ.dəns/ us/ˈɪn.sɪ.dəns/
事件;（事件的）发生率
an event, or the rate at which something happens
There have been quite a few incidences of bullying in the school this year. 今年该校发生了好几起欺凌弱小的事件。
an increased incidence of cancer near nuclear power stations 核电站附近癌症发病率的上升