Year	per 1,000
1990	3.3
1991	3.5
1992	4.7
1993	5.5
1994	3.7
1995	2.9
1996	2.4
1997	2.3
1998	2.4
1999	2.6
2000	2.7
2001	2.6
2002	2.4
2003	2.2
2004	2
2005	1.9
2006	1.9
2007	2.1
2008	2.8
2009	2.4
2010	2.3
2011	2.2
2012	2.2
2013	2.3
2014	2.6
2015	2.9
2016	3.1
2017	2.9
2018	2.7
2019	2.6
2020	2.7
2021	2.7
2022	2.6