fall off
phrasal verb with fall verb uk/fɔːl/ us/fɑːl/ fell | fallen
(数量)减少;(比率)下降;(质量)降低
If the amount, rate, or quality of something falls off, it becomes smaller or lower.
Sales have been falling off recently. 销量最近一直下滑。
Membership of the club has fallen off in recent months. 最近几个月俱乐部的会员人数减少了。