Compare Past Years Data in Bar Chart?

Hello,

So I have been collecting data for almost a year now of how many requests we get and how many requests we send out of our company.

I have the data in a bar chart. However, I want previous years data compared to the current year. For example, May 2012 would also have May 2011 next to it in a bar graph. This would be ongoing since each month gives me more data.

Is this possible? I have attached a screen shot of the bar chart with an illustration showing what I am wondering about?

Thanks!