Comparing Xbox 360 and PS3 first year sales isn't fair. Back when Xbox 360 was released, It was the only next gen console of the time and consumers aren't as ready in upgrading consoles than when PS3 was released. This coupled with the fact that everyone was was waiting for the much hyped PS3, Xbox 360 was struggling with consumer acceptance.
From this standpoint, PS3 was set to benefit. So from the chart above, although the PS3 is running a similar curve with Xbox 360, it's doing worse.