Calculate average percent change for multiple months

[#1]

Hi,

The requirements I have are to calculate a percent change between the current month and prior months values. Then also calculate the YTD average change for all months in the year.

So if my data looks like this...

Month	Current Month
Dec	50
Jan	55
Feb	60
Mar	65

My Percent change for March would be (65-60)/65 = 7.69%. And the table for the year would look as such:

Month	Current Month	Prior Month	% Change
Dec	50	-	-
Jan	55	50	9.09%
Feb	60	55	8.33%
Mar	65	60	7.69%

My calculate for percent change is something similar to:

(SUM({$<Month = {$(=Only(Month))}>}  - SUM({$<Month = {$(=Only(Month) - 1)}>} )/ SUM({$<Month = {$(=Only(Month))}>}

Now they want to get the average YTD change percent. So the YTD change for Feb would be (9.09+8.33)/2 = 8.71%. And I would end up with this table:

Month	Current Month	Prior Month	% Change	Avg YTD % change
Dec	50	-	-	-
Jan	55	50	9.09%	9.09%
Feb	60	55	8.33%	8.71%
Mar	65	60	7.69%	8.37%

Now the question comes in. How can I calculate this Avg YTD % change using QlikView? I would imagine it owuld need to be something like

avg(

     aggr(

          (Calculate % change),

          [Month]

     )

)

but i am not sure how to calculate the % change correctly when doing this over all months. Any help would be appreciated.

Thanks in advanced