Start line chart from the origin

Hi,

I have input control to select the dates from and to. So the chart will display two lines, one current year and other previous year.

Say i select dates from September 2012 to June 2013, in this case the current year should start dates from Jan 2013 to June 2013 and previous year from September 2012 to June 2013. The line chart should start from the origin which is September 2012.

So the graph will be

Sept 2012 (Origin) -  line1

Oct 2012             - line1

Nov 2012  - line1

Dec 2012 - line 1

Jan 2013 - line 2

Feb 2013 - line 2

Mar 2013 - line 2

Apr 2013 - line 2

May 2013 - line 2

Jun 2013 - line 2

Appreciate your help.

Thanks,

Arun