A trend is a general direction or tendency. It is important to identify trends when you write a description of graphical information.
On a simple chart like this it is easy to see that the trend was upwards (there was an upwards trend):
Similarly it is easy to see that the trend in the following graph was downwards (there was a downwards trend):
Sometimes the trend is less obvious and you have to read the graph carefully
In this case you can see that wood production in Italy from 1994 to 2005 went up and down (fluctuated). But overall production declined, from nearly 9.5 thousand cubic metres in 1995 to just over eight thousand cubic metres in 2005. The trend is downwards. Production declined over this period. A program like Microsoft Excel can provide a trendline to show the data series trend:
When describing a graph of this type you should state what the overall trend is (upwards, downward or unchanging), and mention the initial and final figures. You should also mention the lowest and highest points reached. For example, wood production in Italy reached a peak of over eleven thousand cubic metres in 1999. The lowest amount of wood produced in one year was seven and a half thousand cubic metres in 2002.