The US Endangered Species Act, implemented in 1973, created a "perfect duty" to save each species equally, but did not provide for the means to carry it out. The law was passed by legislators unaware of the magnitude of the problem and how difficult it would be for the Fish and Wildlife Service to properly enforce it. It has had little success. Although it has helped some, species recovery has been a dismal 100 to 1 ratio of recoveries. As of 1994 there were 840 endangered species and 21 species that had recovered and had been taken off the list.