reach a plateau 进入平稳状态

By 2002, this improvement had reached a plateau.

到了 2002年，这种上升势头开始进入了一个平稳的阶段。

近义：level out (at... ) / maintain the same level /remain stable 维持在(某个水平上)

The number of cases of the disease remained relatively stable in 2009.

在2009年，该病的病例数量维持在一个稳定的水平上。

反义：fluctuate around... / fluctuate between...and…

Their total leisure time per week fluctuated between 22 hours and 35 hours.

他们每周的空闲时间在22个小时到35个小时间上下波动。