I find it interesting that more time is spent on fleet or in Ops, FP's, and WZ. (and not much on Lvl 1-50 planetary time - i.e. time spent "in the story" of the War between the Sith and the Republic) - that means there are a lot of lvl 50's that are running around without something to do - or they are running the FP's, etc. over and over for a few commendations and getting bored like me. .
You need to read the bit above the graph again. That chart was for level 50s only, and showed no data for planetary time spent levelling. The percentage of game time spent on planets that was shown in the graph was for time spent by 50s doing dailies/gathering/wandering aimlessly, and not for anyone levelling a new char.