口吃的平均人口流行率（prevalence）大约1%，儿童口吃的发生率约为5%，几乎80%的口吃儿童到16岁时自发地恢复了流畅性。
An average prevalence of stuttering is approximately 1 % of the population , and an incidence of stuttering in childhood is about 5 % .
口吃的发生