I'm going to assume that by "at the height of its power" you're referring to the sixteenth century, since that's how that period has traditionally been characterized.

It's very hard to say. We don't have the economic data necessary to give a definitive answer, for while records certainly exist, they are sporadic and often don't provide the type of information which modern researchers are looking for. However, one export which is of undoubted importance was silk and silk products. Raw silk was either imported from Iran (particularly the Gilan region) or, less commonly, home-grown. It was then either manufactured into silk cloth to be exported (an industry which made Bursa prosperous) or re-exported directly to European merchants in its raw form. The silk industries of Europe were entirely dependent on imports of raw silk from the Ottoman Empire, and the Ottomans derived millions of akçe annually in tax revenue from the trade.

Halil İnalcık with Donald Quataert ed. An Economic and Social History of the Ottoman Empire, vol. 1 (Cambridge University Press, 1994), 218-227.