Why does the average Argentine hold more U.S. dollars than the average U.S. citizen?

Estimates are that the value of U.S. dollars circulating in Argentina exceeds

$1,000 per person, which is higher than the per capita dollar holdings in the United States. A number of other countries, including those that once belonged to the former Soviet Union, also hold large quantities of dollars. In all, as much as $600 billion in U.S. currency—about one-third of the total amount issued—may be circulating outside the borders of the United States.

Why do Argentines and other non-U.S. residents hold so many dollars?