Wikipedia has a list that allows sorting by "per 1,000 capita (active)" [0] – scroll to the table and click the rightmost column to sort by active per 1k capita.

By this measure, the US is 51st on the list with a value of 4.2, behind many European countries and NATO members, e.g. Greece is #7 with 13.3.

[0] https://en.wikipedia.org/wiki/List_of_countries_by_number_of...