Overall, the virus, which at its height crippled some 650,000 children a year, now claims less than 150,000 victims annually. As of 1994, the last known case case of polio in the western hemisphere was recorded in September 1991 in Peru. Parts of Africa, the Middle East and the Pacific are also struggling free of the virus. Of the more than 200 nations in the world, 108 have reported no cases of polio for three consecutive years, though not every case of polio is detected. The 80% target for polio immunization has been reached by some 80 countries. A total of 45 countries have already reached the 90% coverage target set for the year 2000. Since 1990, however, 22 nations have let their polio vaccination coverage slip by more than 10%.