A columnist in Barrons said (within the last 12 months) that $500
billion dollars was 85% of the rest of the world's net annual savings.
 Would like to verify that with a source.

I'm not sure it can be truthfully refuted or confirmed. My guess it is
close to correct. Since the big sucess President Bill Clinton had with
lying, cooking the books is the norm. Institutions and corporation
save lots of money, especially if you typically count investing as
savings. The big international companies are 70% in the USA or 17% in
the USA? It is a tough judgement call. Some conspiracy theorists claim
that towns, cities and states have huge amounts secretly saved as they
cry poverty. If this is not true in other countries, The USA may have
half of the world's savings.   Neil