Year	World Bank estimate
1981	47.5
1986	34.4
1989	46.7
1990	45.3
1991	46.6
1992	45.7
1993	46
1994	46.8
1995	45.7
1996	46.5
1997	45.6
1998	45.7
1999	47.7
2000	47.4
2001	51.6
2002	51.9
2003	49.3
2004	48.3
2005	47.5
2006	49.4
2007	49.3
2008	48.7
2009	50.6
2010	48.2
2011	48.7
2012	48.6
2013	49.3
2014	48.6
2015	48.4
2016	48.7
2017	48.3