In response to Sumatra and Sulawesi refusing to hand over their foreign exchange, in June 1957, a new system for foreign exchange was introduced; exporters received export certificates (BE) representing the foreign currency earned and could sell them to importers on the free market (but subject to a 20% tax). This effectively created a freely floating rupiah. The price of the certificates quickly reached 332% of face value by April 1958, i.e. Rp 38, a rate at which the government chose to end the free market, fixing the price at 332% of face value.