The increasing frequency of postal rate increases from the 1970s on, and the necessity to wait for these to be approved by Congress, made it problematic for the Postal Service to provide stamps matching the increased costs in a timely manner. Until it was known, for example, whether the new first-class rate would be 16c or, instead, 15c, no denominated stamp could be printed. The Postal Service found a way to bypass this problem in 1978. Preparatory to that year's increase, an orange colored stamp with a simple eagle design appeared bearing the denomination "A" instead of a number; and the public was informed that this stamp would satisfy the new first-class rate, whatever it turned out to be. Subsequent rate increases resulted in B, C and D stamps, which bore the same eagle design but were printed, respectively, in purple, buff-brown and blue-green. When it came time for an E stamp in 1987, the Postal Service commissioned a more elaborate design: a color picture of the globe as seen from space (E for Earth). Rises since have prompted F for Flower, G for Old Glory and H for Hat stamps, all appropriately illustrated. The F stamp in 1991 was accompanied by an undenominated "make-up" stamp with no pictorial design beyond a frame, which enclosed the words "This U. S. stamp, along with 25c of additional U. S. postage, is equivalent to the 'F' stamp rate."