Year	per 1000 people
1993	3.8
1994	3.7
1995	3.9
1996	4.1
1997	4
1998	4.1
1999	4.2
2000	4.2
2001	4.4
2002	4.4
2003	4.1
2004	4.203
2006	3.7
2008	4.242
2009	3.802
2012	3.861
2013	3.93
2014	3.945
2015	3.898
2016	4.021