Working with percentages

Hello again,

I've been working on a patch in which the idea is to divide a 100% between a series of several number boxes, so whenever you increase the value in one, the value in the rest of the boxes will be decreased evenly so they always match that 100 total. That part is already done, but now I find myself not knowing how to work with those values; the idea is to generate random numbers through a metro and have those random numbers select sounds in time according to the boxes values. I thought about a chain of splits at first, in which I would sum or substract the thresholds values according to the number boxes, but the thing is, I have 65 boxes, thus I'd need 64 splits, which sounds a little too much for me, any ideas?

Thanks in advance!