In 1949, Ethiopia issued a set of overprinted semi-postals (Scott #B6-10) commemorating the National Agricultural and Industrial Exhibition, held in Addis Adaba. Initially, 15,ooo sets were issued, but most sets were not sold, and 10,ooo of each of the low values and 5,000 of the high value were later overprinted again, creating the the 1951 Exposition set (Scott #B16-20). Consequently, B6-10 ultimately had a total quantity issued of 5,000. Scott '09 values B 6-10 unused at $ 49.00 and B 16-20 at $ 25.00, and I feel that both catalog values are absurdly low. Many similarly undervalued Ethiopian issues exist, however, and I intend to recommend some of them in the future.
Ethiopia is still a poor country, with an estimated population of over 85 million people, but it has one of the fastest growing economies in the world, with annual GDP growth of 9%-11%. It has the greatest water reserves in Africa, and is one of its most fertile countries. According to the New York Times, it has the potential "to become the breadbasket for much of Europe
if its agriculture were better organized."
Ethiopia has a fascinating philatelic history, and most serious collectors who specialize in Ethiopia are Europeans and Americans. I expect that this will change over the long-term, as it has for so many countries which have risen out of poverty.