Year	per 1,000
1990	4.6
1991	6.3
1992	11.2
1993	17
1994	15.4
1995	9.7
1996	6.6
1997	6.2
1998	6.4
1999	5.9
2000	4.9
2001	4.2
2002	4
2003	4
2004	4
2005	4
2006	3.9
2007	3.8
2008	4.2
2009	3.6
2010	3.5
2011	3.5
2012	4
2013	3.5
2014	3.5
2015	3.5
2016	3.4
2017	3.2
2018	3.1
2019	3.5
2020	11
2021	4.6
2022	4.4