Year	World Bank estimate
1987	43.5
1994	41.3
2002	41.4
2003	42.2
2004	41.3
2005	42.6
2006	39.6
2007	38.4
2008	39
2009	39
2010	38.8
2011	40
2012	40.2
2013	40.2
2014	41.2
2015	42.9
2016	41.9