Variance from month to month

[hammermill21]

Hello,

I'm trying to use a waterfall chart to show the variance from month to month but I'm just not getting it to work correctly. To calculate each month percent I use this expression:

For Feb:

(Count({<[UMHC SYSTEM]={'100%'},[EC-LS-EM]= {'EC'}, Month = {'Feb'}>} [UMHC SYSTEM])/16  )

/

(  Count({<[EC-LS-EM]= {'EC'}>} EP#) / (16 * count({<Date={'<=$(=today())'}>}distinct Month))  )

Which would be 42%

then for March, it is:

(Count({<[UMHC SYSTEM]={'100%'},[EC-LS-EM]= {'EC'}, Month = {'Mar'}>} [UMHC SYSTEM])/16)

/

(Count({<[EC-LS-EM]= {'EC'}>} EP#) / (16 * count({<Date={'<=$(=today())'}>}distinct Month)))

Which would be 50%

So what I'm trying to show the variance from month to month, depending what months are selected. How can I go about doing that?

Thanks!