Hello Yanxia,
I think there's been a misunderstanding about the data. For the month of August the number of accidents has been corrected (from my colleague Michael Winkler), see table below. That means there weren't 12 accidents, only 3.
How's that in September? Was there actually 7 accidents, or is that the number of days?
Now the cumulated data is not correct! If there were actually 7 accidents, then the Actual cumulation should be 20!
I'm waiting for your feedback on the correctness.
Please send us your feedback as soon as possible.