Year	% of population
1989	30.5
1990	28.4
1991	44.6
1992	33.9
1993	24.4
1994	22.8
1995	27.5
1996	26.1
1997	19.9
1998	15.9
1999	16.9
2000	18.7
2001	16.9
2002	19.7
2003	19.1
2004	16.9
2005	14.8
2006	14.3
2007	9.9
2008	12.3
2009	16.5
2010	17.6
2012	19.9