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

Executive Directors and Under-Secretaries General of the UN
2011present Dr Babatunde Osotimehin (Nigeria)
20002010 Ms Thoraya Ahmed Obaid (Saudi Arabia)
19872000 Dr Nafis Sadik (Pakistan)
196987 Mr Rafael M. Salas (Philippines)

Who was Executive Director or Under-Secretary General from 2000 to 2010?
Thoraya Ahmed Obaid