Between 1991 and 2004, only 20 U.S. patents for inventions [but not including design patents, plant patents, re-issue patents, etc.] were granted to citizens from LDCs, compared with 14,824 from other developing countries, and 1.8 million to citizens of rich countries.

United Nations Conference on Trade and Development. 2006. The Least Developed Countries Report 2006.

http://www.unctad.org/en/docs/ldc2006_en.pdf

LDC's: Afghanistan, Angola, Bangladesh, Benin, Bhutan, Burkina Faso, Burundi, Cambodia, Cape Verde, Central African Republic, Chad, Comoros, Democratic Republic of the Congo, Djibouti, Equatorial Guinea, Eritrea, Ethiopia, Gambia, Guinea, Guinea-Bissau, Haiti, Kiribati, Lao People's Democratic Republic, Lesotho, Liberia, Madagascar, Malawi, Maldives, Mali, Mauritania, Mozambique, Myanmar, Nepal, Niger, Rwanda, Samoa, Sao Tome and Principe, Senegal, Sierra Leone, Solomon Islands, Somalia, Sudan, Timor-Leste, Togo, Tuvalu, Uganda, United Republic of Tanzania, Vanuatu, Yemen and Zambia.

Source: Knell, M. 2006. Uneven Technological Accumulation and Growth in the least developed countries. Background paper prepared for The Least Developed Countries Report 2006, UNCTAD, Geneva.