Horn of Africa at the 2012 London Olympics. According to the IMF, in 2010 the Horn of Africa region had a total GDP (PPP) of $106.224 billion and nominal of $35.819 billion. Per capita, the GDP in 2010 was $1061 (PPP) and $358 (nominal). States of the region depend largely on a few key exports: Over 95% of cross-border trade within the region is unofficial and undocumented, carried out by pastoralists trading livestock. The unofficial trade of live cattle, camels, sheep and goats from Ethiopia sold to other countries in the Horn and the wider Eastern Africa region, including Somalia and Djibouti, generates
German horn excessive. Although the French firm Jérôme Thibouville-Lamy in about 1928 introduced a piston-valved double-horn with ascending third valve, designed in collaboration with the horn player Louis Vuillermoz, the double horn has continued to be identified mainly as a German horn. The double horn essentially combines two instruments into a single frame: one horn in F, and a second, higher horn keyed in B. Like the single horn it has three valves, but each has a double set of tubing, the first tuned in F and a shorter set in B. By depressing a fourth valve (usually operated by the thumb),