General SDR allocations are to be based on “a long-term global need to supplement existing reserve assets,” with decisions made for successive periods of up to five years. So far, such allocations have been made only three times, in 1970-72, in 1979-81, and in 2009, with the latter allocation, amounting to $250 billion, being part of the recovery package adopted by the G-20 to manage the global financial crisis.