I'm attempting to create a stacked bar chart (with 4 different areas) that make up a rolling 12 months total. i.e. for bar one I would want to show data for May 2012 - April 2013, then bar two June 2012 - May 2013 etc etc. Whilst I can do this as a total for each 12 month period (by creating a seperate expression per 12 month period), I am having an issue with the stacked element showing the split of the 4 areas.
Based on the attached spreadsheet does anything have any suggestions?