Excel 2003 - I created a simple bar graph, but each set of bars is far from the other. How do I get em closer?

I created a bar graph that has 3 sets of 2 bars. Each set of 2 bars is close to each other but far from the other sets. Such as,

_ _ ....... _ _ ...... _ _



(the tops jst represent space)



I want them closer to each other, but I cant figure out how! Please help!