Values In Array Joining Not Adding (e.g. Ƈ+2' = ཈', Not Ɖ')

I have 8 peices of data in an Array and I need to add the final 6 to give me a total, but the results are not what I expected. Array example - Code:

var Networking_2009_1 = ['Justin Hopkins','JBH','1','2','3','4','5','6'];

I am adding the values like this -

Code:
var feeEarnerTotal = 0;
for(t in Networking_2009_1)
{ if(t > 1) // 0 and 1 are the Long Name and Short Name, so must be skipped
{ feeEarnerTotal = feeEarnerTotal + Networking_2009_1[t]; }
}

The problem is that when the value is output to the screen it is '123456' rather that '21' as expected. I suspect this is because there is writte data also in the Array, but I'm not sure how to fix it.