Colin
The reason 2times as many use PS is the broad nature it covers, not only photographers are using PS, it is used by a multitude of other industries.
More and more photographers switch to using LR as their primary database/processer during each cycle as LR becomes more powerful. I have both CS5 and LR4 and came into PS later than most. I predominantly use LR, as it is definitely easier to use and with plugins is a very capable and fast (think workflow) software. Add a software such as NIK to it with NIK's control points and it is a stunning combination that takes images to great places without the tedious labor of masks and layers.