In 1960 the German mark had a fixed exchange rate with the US dollar which, in turn, was officially fixed to gold.

FORBES: A Sound Currency Standard Keeps Inflation Quiet

He owns a workshop as a metal turner and his business is affected by the rate of exchange of the US dollar, which has fluctuated a lot recently.

BBC: Noura

Families in Mexico who depend on the income sent to them from workers abroad are also suffering from the unfavourable exchange rate of the Mexican peso against the US dollar - with the US dollar falling 8% this year.

BBC: Mexicans sending home less money

The central bank's website showed the exchange rate as 11, 180 rial to one US dollar.

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Since the rules were introduced in November 2011, Paypal has been used as an alternative means of obtaining the US currency close to the official exchange rate, which currently stands at about 4.7 pesos per dollar.

BBC: Paypal suspends domestic transactions in Argentina