The only thing I can see from this graph is that:
a. European games sell better on the PS3 usually (like scottie saw)
b. That as "Time" passed (no actual time increments given), the PS3 user base grew. Thus the overall percentage of people on the 360 buying the game as opposed to people with a PS3 buying the game naturally declined.
When this graph started (beginning 08) the PS3 stood at 57% the total sales of hardware as compared to the 360 (9.16 million and 16.01 million respectively). Today, after a full year of sales, the numbers are 21.4 million PS3 and 29.6 million 360. Guess what happened to the percentage of total PS3 sales compared to the Xbox 360!?! It went up to 72% even after selling less than the 360 last year.
So, since this chart is based solely on percentages, this shows you why it is declining, and why this is not only absolutely normal, but this indicates that the PS3 software sales is not catching up anywhere near what the author intended it to look like.







