Shortening Graph Lines for Zero Values
By default, a line graph based on a data range in Excel will show zero values on the graph, instead of breaking the data lines where the zero values appear.
The lines can be changed so there are gaps on the axis where there is no given value. Right click on the graph, and click 'Select Data'. Click on the 'Hidden and Empty Cells' box in the lower left of the dialog box. Choose the option to show empty cells as gaps.
Then remove the zeroes listed in the data range on which the graph is based. The lines in the graph will be correspondingly shortened.