Just curious about how AP is scored

I’m just one of the striving APers, and I just got curious of all the score curves of AP exam.
So, I looked in, and WOW! I thought the curve would be all similar, but it wasn’t!
The most surprising part was that there are only approx. 4%of 5’s in Chinese!

Therefore, I came to this question : How the heck is AP scored?!
I can’t understand the algorithm of scoring… Please, somebody help me-!
I won’t be able to assume my score after AP few days after! I’ll just have to wait for the miracle!

It depends on the subject. For example, below link shows how the scores for the 2009 English Lit exam were calculated.
http://apcentral.collegeboard.com/apc/public/repository/english-literature-released-exam-2009-scoring-worksheet.pdf

68% got a 5 last year
http://media.collegeboard.com/digitalServices/pdf/ap/apcentral/ap14-chinese-lang-score-dist.pdf