Read this and answer the question. If the question is unanswerable, say "unanswerable".

The ESA requires that critical habitat be designated at the time of or within one year of a species being placed on the endangered list. In practice, most designations occur several years after listing. Between 1978 and 1986 the FWS regularly designated critical habitat. In 1986 the Reagan Administration issued a regulation limiting the protective status of critical habitat. As a result, few critical habitats were designated between 1986 and the late 1990s. In the late 1990s and early 2000s, a series of court orders invalidated the Reagan regulations and forced the FWS and NMFS to designate several hundred critical habitats, especially in Hawaii, California and other western states. Midwest and Eastern states received less critical habitat, primarily on rivers and coastlines. As of December, 2006, the Reagan regulation has not yet been replaced though its use has been suspended. Nonetheless, the agencies have generally changed course and since about 2005 have tried to designate critical habitat at or near the time of listing.

What is the time limit for designating a species critical habitat after the species has been added to the endangered list?
within one year