Overlay two years in bar chart

Hello fellow excel users again,

I have a long dataset with many hundreds of dates in one column for a databse. It is used to see if we are sending and receiving more packages on a year by year basis.

What i would like is a visual representation of this data which I can do quite easily in a bar graph whcih splits it into months and years. What i don't know how to do easily is overlay or overlap the two years of data in the one bar graph for the same month.

Essentailly what i want is a bar graph from Jan to December month by month. Then red bars (can be any colour) for 2011 number of received packages in a given month and blue overlapped or adjacent to it in same month of chart for the 2012 received number of packages.

I know how to do this when I have two seperate columns of data for different years. But can't figure it out when two different years are in the same column.

UPDATE: Essentially I want to have something like this for the 2011 and 2012 year with two different coloured bars to distinguish the different years for each each month. But don't know how to do it when the date for 2011 and the data thus far for 2012 comes from the same column :-S

If you go to this website and scroll down to overlapped bar charts, I think you will find what you are looking for.

http://peltiertech.com/WordPress/example-charts/

It sounds to me as though a pivot chart would suit. Group the dates on month and year and use year as the series.