求翻译：从关系图可以看到很大的变化发生了的培训类的数目在过去的十五年。一方面，在 90 年代前, 增加培训类的是不太大。另一方面，有急剧增加培训类在 90 年代后。是什么意思？

From the diagram you can see the great changes occurred in the number of training classes in the past fifteen years. The one hand, in the 1990s to increase the training class is not too large. On the other hand, there is a sharp increase in the training class in the 1990s.

You can see from the Relationship Diagram of a very large changes have occurred in the number of training classes in the past 15 years. On the one hand, 90 years ago to increase the number of training classes is not too large. On the one hand, there has been a sharp increase in training class in the

May see from the relational graph the very big change has occurred training class number in past 15 years.At the same time, before 90's, increase training class not too big.On the other hand, has sharp growth training class after the 90's.

From the diagram you can see a lot of changes in number of training classes that have taken place over the past 15 years. On one hand, in front of the 90 's, increasing training class is not too big. The other hand, a sharp increase in training after class in the 90 's.

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