How to Create a Line Chart

This article describes how to go from a crosstab that contains a date or time variable in the rows...

...to a state where the data is represented by a line chart to see trends over time:

Requirements

You will need a date/time variable, along with a variable that you would like to see trended over time.

From the toolbar, click Visualization > Line > Line.
In the object inspector, go to Data > Data Source and select your date/time variable in the Variables dropdown and the variable being trended over time from the Groups drop-down. Alternatively, if you have already created a crosstab on a Page, you can select it from the Data dropdown.
Tick the Calculate automatically box. Any changes in your data or settings will then be shown automatically.