CFETS RMB Index

I made a spreadsheet to calculate the CFETS RMB Index in real-time, but I'm not sure the original exchange rates at the start of the index. I calculated 103.21 as the index for 2015-11-30, which CFETS says was 102.93. Since currencies are constantly shifting, I don't know if my calc is wrong or the exchange rates are different (perhaps different closing times).

For 2015-12-31 I calculate the index as 101.36, the official index was 100.94.

2016-01-08 I calculate 100.60, CFETS says 99.96.

So this is a work in progress. I sent an email to CFETS to see what I could learn...