Tulip mania (Dutch: tulpenmanie) was a period during the Dutch Golden Age when contract prices for some bulbs of the recently introduced and fashionable tulip reached extraordinarily high levels, and then dramatically collapsed in February 1637. It is generally considered to have been the first recorded speculative bubble or asset bubble in history. In many ways, the tulip mania was more of a thitherto unknown socio-economic phenomenon than a significant economic crisis. It had no critical influence on the prosperity of the Dutch Republic, which was one of the world's leading economic and financial powers in the 17th century, with the highest per capita income in the world from about 1600 to about 1720. The term 'tulip mania' is now often used metaphorically to refer to any large economic bubble when asset prices deviate from intrinsic values. In Europe, formal futures markets appeared in the Dutch Republic during the 17th century. Among the most notable centered on the tulip market, at the height of tulip mania. At the peak of tulip mania, in February 1637, some single tulip bulbs sold for more than 10 times the annual income of a skilled artisan. Research is difficult because of the limited economic data from the 1630s, much of which come from biased and speculative sources. Some modern economists have proposed rational explanations, rather than a speculative mania, for the rise and fall in prices. For example, other flowers, such as the hyacinth, also had high initial prices at the time of their introduction, which then fell as the plants were propagated.