I should add that you could assume that each title, when the costs/profits are distributed over all available titles, has approximately the same profit margin.
Thus, if the dev costs, relative to the profits (not overall -- there's an important distinction here), per title are the same across all three next-gen platforms (and I think this might be an incorrect assumption, but it is possible), then you could consider 3rd party success as a mere average number of 3rd party software units sold, per title -- which MS shows in their graph, and then pollutes it with their extra year lead (giving 1st-year releases up to an additional year of sales, as padding, in addition to a boost to the number of available hardware units, during that 1st year when MS didn't have next-gen competition).
Nintendo's graph is... pretty empty of relevant info, really. All it really shows is that more 3rd party software units have been produced for the Wii, which goes hand-in-hand with the Wii being the most numerous console for a large portion of this generation, and demonstrating a "sells like hotcakes" outlook for nearly its entire existance on the market. If anything, I think the overall 3rd party units sold on what is, by far, the most popular platform, is a little underwhelming.
