customize histogram

[gabriele_b]

Hi,
I have to chart some data with an histogram.
the data are similar to:
January
data A gen 2014
data A gen 2013

data B gen 2013
data B gen 2014

data C gen 2013
data C gen 2014

February
data A 2014
data A 2013

data B 2013
data B 2014

data C 2013
data C 2014

and so on.
what I need, is to have the single couple of data separated from the other. I don't know if excel has an option to do this. the only option I discovered is to chart all the data with the same spacing.
I tried with an empty serie, but I need to show the legend and so the empty serie appears... and I don't want this....
this is the best way I found to show the difference between several data in different years and month. I have to present this chart to somebody that is not very pratical for graphics and so I need something simple and easy to understand.... if you have any suggestion you are welcome!
Here I attach a simple image of what I need
thanks a lot!!!!

Gabriele