Need items grouped by country of origin with percentage of total

I have a list of materials that I maintain with country of origin. Something like this:

1 USA

2 CHINA

3 FRANCE

4 USA

5 MALAYSIA

What I would like is to paste a bill of materials and have the items summed by country and expressed as a percentage of the total.

So this

1 50

2 25

4 50

Becomes this:

USA 80%

CHINA 20%

I can think of a couple ways to maybe start tackling this but figured the experts here have the cleanest/easiest way.