Presenting data from categories over time – linecharts

Sometimes you do not only have categories: e.g. countries, but you have values over time. This is where line charts are quite handy. A line chart looks like:

On the y axis we still have our values on the x axis we have the time measured. This graph works best if the time interval between the measurements is equal (Of course line charts are not limited to timeseries). Again it’s important, when comparing multiple categories, to start your y axis with 0. Only when displaying a single line it’s ok to start somewhere in between – but give a relation – say where your graph starts and where it ends.