Question:
Who was the chair of Economic Community of West African States in Jan, 1999?

Context:
 Alassane Dramane Ouattara is the chair of Economic Community of West African States from Feb, 2012 to Feb, 2013. 
 John Kufuor is the chair of Economic Community of West African States from Jan, 2003 to Jan, 2005. 
 Siaka Probyn Stevens is the chair of Economic Community of West African States from Jan, 1981 to Jan, 1982. 
 Abdoulaye Wade is the chair of Economic Community of West African States from Dec, 2001 to Jan, 2003. 
 Mathieu Kérékou is the chair of Economic Community of West African States from Jan, 1982 to Jan, 1983. 
 Mahamadou Issoufou is the chair of Economic Community of West African States from Jun, 2019 to Jun, 2020. 
 Lansana Conté is the chair of Economic Community of West African States from Jan, 1984 to Jan, 1985. 
 Blaise Compaoré is the chair of Economic Community of West African States from Jan, 2007 to Dec, 2008. 
 Olusegun Obasanjo is the chair of Economic Community of West African States from Sep, 1977 to Sep, 1979. 
 Abdou Diouf is the chair of Economic Community of West African States from Jan, 1992 to Jan, 1993. 
 Faure Essozimna Gnassingbé Eyadéma is the chair of Economic Community of West African States from Jun, 2017 to Jul, 2018. 
 Mamadou Tandja is the chair of Economic Community of West African States from Jan, 2005 to Jan, 2007. 
 Yakubu Gowon is the chair of Economic Community of West African States from May, 1975 to Jul, 1975. 
 Muhammadu Buhari is the chair of Economic Community of West African States from Jul, 2018 to Jun, 2019. 
 John Mahama is the chair of Economic Community of West African States from Feb, 2013 to May, 2015. 
 Nicéphore Soglo is the chair of Economic Community of West African States from Jan, 1993 to Jan, 1994. 
 Ahmed Sékou Touré is the chair of Economic Community of West African States from Jan, 1983 to Jan, 1984. 
 Abdulsalami Abubakar is the chair of Economic Community of West African States from Jun, 1998 to Jan, 1999. 
 Umaru Musa Yar'Adua is the chair of Economic Community of West African States from Dec, 2008 to Feb, 2010. 
 Sani Abacha is the chair of Economic Community of West African States from Jul, 1996 to Jun, 1998. 
 Ellen Johnson Sirleaf is the chair of Economic Community of West African States from Jun, 2016 to Jun, 2017. 
 Jerry Rawlings is the chair of Economic Community of West African States from Jan, 1994 to Jul, 1996. 
 Goodluck Jonathan is the chair of Economic Community of West African States from Feb, 2010 to Feb, 2012. 
 Étienne Gnassingbé Eyadéma is the chair of Economic Community of West African States from Jan, 1999 to Jan, 1999. 
 Alpha Oumar Konaré is the chair of Economic Community of West African States from Jan, 1999 to Dec, 2001. 
 Léopold Sédar Senghor is the chair of Economic Community of West African States from Sep, 1979 to Dec, 1980. 
 Nana Akufo-Addo is the chair of Economic Community of West African States from Jun, 2020 to Dec, 2022. 
 Macky Sall is the chair of Economic Community of West African States from May, 2015 to Jun, 2016.

Answer:
Étienne Gnassingbé Eyadéma