开头:
It is obvious in the graphic/table that the rate/number/amount of Y has undergone dramatic changes. It has gone up/grown/fallen/dropped considerably in recent years (as X varies). At the point of X1, Y reaches its peak value of …(多少).
分析:
What is the reason for this change? Mainly there are … (多少)reasons behind the situation reflected in the graphic/table. First of all, …(第一个原因). More importantly, …(第二个原因). Most important of all, …(第三个原因).
结尾:
From the above discussions, we have enough reason to predict what will happen in the near future. The trend described in the graphic/table will continue for quite a long time (if necessary measures are not taken括号里的使用于那些不太好的变化趋势).