Development costs

Although I read this piece on Eurogamer with interest, I actually think that it's quite unclear what is meant by average development costs. For instance, taking only 13 XBox titles makes it very subjective and could be designed to make the other platforms appear better to develop for.

What's also not clear is whether those average figures are for titles developed exclusively for that platform or for titles that are spread over a number of platforms. If it's the latter, should we then assume that the average development cost of a game is 388 million Yen (or 2.87 million Euro)?