You have time series data and don’t know which chart to use.  What are you going to do?  Should you always use a line chart if you have time series data? Well, that depends.  Generally speaking, a line chart is used to convey trends across time. If you had data on monthly operating costs, a line chart would be an appropriate chart to use because you could see how the costs fluctuate over the course of the year.  Or, as in the case below, a line chart is used to effectively illustrate 500 px’s accelerating user base  growth in various intervals between 2009 and 2011.



However, if you need to show relative proportional changes over time, you’ll want to use a 100% stacked column chart. The 100% stacked column chart below shows the proportion premium games and freemium games contribute to game app revenues over two time periods. If you had data for a single month, then a pie chart would have been appropriate because pie charts used to show proportional relationships in a specific moment in time.