Feedback calculation error

[lancasterrobotics]

Currently, my feedback score is 99.1. Not great I know but I have been working diligently to correct any issues. Today for some reason I looked at the score closer. I have 267 positive feedbacks over the past 12 months and 2 negatives.  By my calculating, this is over 99.25% positive. So when I checked eBay is factoring the percentage from 214 positive feedbacks.  Why are 53 feedback ratings not counted? 

[nobody*s_perfect]

If a buyer purchases multiple items in one week, eBay only counts one of their feedback.

[loveyourimagination49]

Multiple feedback from the same buyer in the same week only count as 1.