Gamasutra
Comparing each system within their first 23 months on sale, the Xbox 360 had the highest third-party software tie ratio at 5.2, followed by the PS3 with 4.4 and the Wii with 3.1. The Xbox 360 has since gone on to establish a combined first- and third-party ratio of 8.1 after 35 months on the market. Interestingly, the Wii's ratio has remained quite consistent throughout 2008 -- certainly a positive result in the face of continued success in the hardware arena. Remember, a high attach ratio may sometimes indicate diminishing hardware sales, with consumers spending more on software as a system matures.
