In the global silver trade from the 16th to 18th centuries, the Ming Dynasty was stimulated by trade with the Portuguese, Spanish, and Dutch. Although global, much of that silver ended up in the hands of the Chinese and China dominated silver imports. Between 1600 and 1800 China received 100 tons of silver on average per year. A large populace near the Lower Yangzte averaged a hundreds of taels of silver per household in the late 16th century. Altogether, more than 150,000 tons of silver were shipped from Potosí by the end of the 18th century. From 1500 to 1800, Mexico and Peru produced about 80% of the world's silver with more than 30% of it eventually ending up in China (largely because of European merchants who used it to purchase exotic Chinese commodities). In the late 16th and early 17th century, Japan was also exporting heavily into China and the foreign trade at large. Trade with European powers and the Japanese brought in massive amounts of silver, which then replaced copper and paper banknotes as the common medium of exchange in China. During the last decades of the Ming the flow of silver into China was greatly diminished, thereby undermining state revenues and indeed the entire Ming economy. This damage to the economy was compounded by the effects on agriculture of the incipient Little Ice Age, natural calamities, crop failure, and sudden epidemics. The ensuing breakdown of authority and people's livelihoods allowed rebel leaders such as Li Zicheng to challenge Ming authority.