I don't remember where I got it from, but somehow I remember seeing somewhere that 30 out of the 130 questions are unscored questions.
In the detailed score report, it states "The percentage is based on both scored and unscored items and was not used to calculate your letter grade." So in other word, we can't even tell from those percentage info how we really did on the scored portion of the exam.
Although, based on what percentage of each area they give you, you can use that to calculate how many correct answers you got out of the 130 questions. I made a B on one of the test, and from my calculation I got 71 questions correct out of 130. If 71 is a B, which is 80%, then the scored questions should be 88.75 or about 88 questions. This would make the amount of unscored questions 42.
hope my input helps a little... Let me know too if you find any more info on how they score the exam =)