Álvaro de Bazán designed the definitive model of the galleon in the 1550s. Casa de Contratación Spain controlled the trade through the Casa de Contratación based in Seville, a river port in southern Spain. By law, the colonies could trade only with Seville, the one designated port in the mother country. Maritime archaeology has shown that the quantity of goods transported was sometimes higher than that recorded at the Archivo General de Indias. Spanish merchants and Spaniards acting as fronts (cargadores) for foreign merchants sent their goods on these fleets to the New World. Some resorted to contraband to transport their cargoes untaxed. The Crown of Spain taxed the wares and precious metals of private merchants at a rate of 20%, a tax known as the quinto real or royal fifth. By the end of the 16th century, Spain became the richest country in Europe. Much of the wealth from this trade was used by the Spanish Habsburgs to finance armies to protect its European territories in the 16th and 17th centuries against the Ottoman Empire and most of the major European powers. The flow of precious metals in and out of Spain also stimulated the European economy as a whole. The flow of precious metals made many traders wealthy, both in Spain and abroad. As a result of the discovery of precious metals in Spanish America, Spain's money supply increased tenfold. The increase in gold and silver on the Iberian market caused high inflation in the 17th century, affecting the Spanish economy. As a consequence, the Crown was forced to delay the payment of some major debts, which had negative consequences for its creditors, mostly foreign bankers. By 1690 some of these creditors could no longer offer financial support to the Crown. The Spanish monopoly over its West and East Indies colonies lasted for over two centuries. Decline, revival and abolition The economic importance of exports later declined with the drop in production of the American precious metal mines, such as Potosí. However, the growth in trade was strong in the early years. Numbering 17 ships in 1550, the fleets expanded to more than 50 much larger vessels by the end of the century. By the second half of the 17th century, that number had dwindled to less than half of its peak. As economic conditions gradually recovered from the last decades of the 17th century, fleet operations slowly