Typically the military seizes power in the midst of a crisis and attempts to restore order and rationalize the economic system. Whatever promises are made to the population, there is a tendency for the military to retain their hold over the political institutions. Examples include: Argentina (1966 and 1976), Bolivia (1971), Brazil (1964), Chile (mid-1973), Indonesia (1966), Turkey (1971 and 1980), and Uruguay (mid 1970s). Of the 45 black African nations, in 1990 23 were military dictatorships where no political parties were permitted.