It looks like a bimodal distribution of some kind.

它看起来像某种双峰分布。

So it's possible you actually have a bimodal distribution.

所以有上有一个双峰分布。

So it's also possible it could be bimodal.

所以它也有双峰的。

It was pretty bimodal where we had India, China, Africa were poor and then Europe, U.S., Japan starting to be fairly well-off and not much in the middle.

那时的印度、中国以及非洲都十分贫穷的。那时的欧洲，美国和日本正走向富强之路，位于中间的国家并不多。

Myasthenia gravis preferentially affects young women in their 20s and 30s and older men in their 60s and 70s, but the cause of this odd " bimodal" distribution of age-of-onset isn't quite clear.

重症肌无力易影响二三十岁的年轻女性和六七十岁的老年男性，但这种奇怪的“双峰”发病年龄分布的原因尚不清楚。