Dear Ngozi, a time series for the period you are looking for might not be available from a unique source. It also depends on the available household or living standards surveys (or main official poverty data sources). My suggestion is to start with NBS (official figures) annual statistics reports available at http://www.nigerianstat.gov.ng and then fill the missing years with information from:
You could also add the report on poverty in Nigeria from the Proceedings of the Nigerian Economic Society. Sorry, I can not immediately recollect the date????
The "LSMS (Living Standard Measurement Study) - Integrated Surveys on Agriculture General Household Survey Panel" could help. This survey was conducted by the World Bank and the National Bereau of Statistics in 2010/2011 (Wave 1), 2012/2013 (Wave 2) and 2015/2016 (Wave 3). Good Luck!