Puerto Rico has roughly $70 billon outstanding debt for a population of four million inhabitants. Qaiqabad struck coins in gold, silver, copper and billon. The city coinage consisted of billon 2, 3, 6 and 15 Kreuzer coins. Provincial coins were issued in silver, billon and bronze denominations, though never gold. They were copied from the Spanish dinero and were consequently minted in billon. Gold, Silver and Billon coins are known for Ala al-Din Masud Shah. The billon coins (5% to 15% silver) were replaced by Cupronickel and Nickel in 1879. In Europe, Switzerland pioneered the nickel "billon" coinage in 1850, with the addition of silver. Billon coins were struck from both Budayun and Dehli. The use of billon coins dates from ancient Greece and continued through the Middle Ages. Analysts expect $35 billon of investment for each type. It was struck at Brindisi and Messina with accompanying billon deniers. Since 2006 a total of $4.56 billon has cut from the educational system. Currently, Detlef Zell and Michel Billon hold this office. There is no mining process in Billon architecture.