The seven most frequently traded currencies
(USD, EUR, JPY, GBP, CHF, CAD, and AUD)
are called the major currencies. All other currencies are
referred to as minor currencies. The most frequently
traded minors are the New Zealand Dollar (NZD),
the South African Rand (ZAR), and the Singapore Dollar (SGD).
After that, the frequency is difficult to ascertain because of
perpetually changing trade agreements in the international arena.