Sum column based on Parameter

Hello,
Taking the data you have presented at face value, you can consider the following measure:

CustomerCount = 
VAR _MF = CALCULATE(SUM('DataTable'[Customer Count]),FILTER('DataTable',NOT ISBLANK('DataTable'[Mutual Funds])))
VAR _GIC = CALCULATE(SUM('DataTable'[Customer Count]),FILTER('DataTable',NOT ISBLANK('DataTable'[GIC])))
VAR _SGD = CALCULATE(SUM('DataTable'[Customer Count]),FILTER('DataTable',NOT ISBLANK('DataTable'[CASH])))

RETURN
if(
    HASONEVALUE(Parameter[Parameter Order]),
    SWITCH(
        VALUES(Parameter[Parameter Order]),
        0, _MF,
        1, _GIC,
        2, _SGD     
    )
)

One note: in order to get the table to work and get the result as intended, I did have to create an additional index column so that each customer count can be attributed to a single "index". I had initial problems where it would combine similar customer counts as a single entity, if that makes sense? 

My parameter looks like this:

Parameter = {
    ("Mutual Funds", NAMEOF('DataTable'[Mutual Funds]), 0),
    ("GIC", NAMEOF('DataTable'[GIC]), 1),
    ("CASH", NAMEOF('DataTable'[CASH]), 2)
}