First of all, let me say something that is widely known but for some reason isn't mentioned much on this site. American students have a vastly different experience with the physics GRE than international students. There are a multitude of reasons for this, however, admissions committees know this and have different standards for international students vs. American students. With that being said, a 55% isn't a poor score really.
Okay, the real reason that I wouldn't bother putting it into a personal statement is that it won't matter. If they actually read your personal statement, you've already got a good enough score for them to be reading your personal statment. Having been a graduate student now for a few years, I know the unimaginable torture it is to grade papers. I can only imagine the hellish tedium of reading 50 personal statements, let alone the 300+ it would be if they didn't prescreen with GRE scores and GPA's.
Try to keep that in mind when you write your personal statements, a lot of times less is more.