Note that at the time, Star Wars was out of print - West End Games had lost the license, and WOTC had not yet produced the d20 version. I'm not 100% sure, but I believe "Palladium" refers to all Palladium games as a group.
As for GURPS' commercial success, I believe it is somewhat larger than the above table indicates, because many people buy GURPS books in order to loot them for their own campaigns in other systems. However, I doubt that factor is large enough to compensate for the difference between 3% of RPGers and 16%.