I am trying to find the trend of a variable or a feature over a period of time. That is no of sales done by a sales representative over a period of time.

Lets say:

Year No.of.sales

2012 10

2013 12

2014 16

2015 18

Looking at this figures, I can say that, the performance of the sales representative is gradually increasing over the period. And, the no of sales are decreasing, then the performance is decreasing and so.on,.

I wanted a statistical method to find the trend within the single variables.

If I have two variables, then I would have seen Correlation. But, I need to see the trend of the sales. What is the **statistical technique** I can use, which gives me a **standardized value**.