@bjorn are you sure you want this to be your conclusion? Let's try to remember that oversimplifications and generalizing takes us further from the truth.
Also one thing about the graph you posted, you can't take statistics out of context. There should be a 'white on white' as well as 'black on black' category listed, at the very least as a 'control'. I'm willing to bet you can't make the same assertions if those are included. Again, there is usually more to those types of stats than 'hey they look different I must hurt them'.