Count of records with specific values

[#1]

Hi, 

I am working on a project where I have ID and attendance indicator for each ID (0 - Attended, 2 - Non - Attendance). I need to calculate the cumulative non - attendance rate as shown below. I need to know cumulative count of Non - attendance and divide by total count of that ID. This needs to be calculated on cumulative basis. 

Appreciate if anyone can help me with a formula / script to accomplish this.  Thanks in advance.

ID	Attendance Indicator	No - Show rate
X_1	0	0%
X_1	0	0%
X_1	2	33%
X_1	0	25%
X_2	2	100%
X_2	0	50%
X_3	0	0%
X_3	2	50%
X_3	2	66%

[#2 · Accepted solution]

Here is a formula that will do what you want

Col Cumulative Sum( If( :Attendance indicator == 2, 1, 0 ), :ID ) /
Col Cumulative Sum( 1, :ID )

[#3]

Thanks Jim for answering all my queries. You have been very helpful.