Show months that have no board entries as null on the chart wizard.

We are using the chart wizard to show a particular value aggregated across items each month for analysis. However, if the board doesn’t have any items for a particular month that month will not show on the x axis. I need to make sure every month is shown on the chart so we can immediately see months that have no entries. I am not “show empty values.” I just need to have every month represented on the x (or Y) axis and if there are not items for that month show it as 0. Any ideas?