Year	per 1,000
1990	2.1
1991	2.1
1992	2.1
1993	2
1994	1.9
1995	1.9
1996	1.9
1997	1.8
1998	1.8
1999	1.7
2000	1.7
2001	1.6
2002	1.5
2003	1.5
2004	1.4
2005	1.4
2006	1.4
2007	1.3
2008	1.3
2009	1.2
2010	1.2
2011	1.6
2012	1.1
2013	1.1
2014	1
2015	1
2016	1
2017	1
2018	1
2019	1
2020	1.1
2021	1.1
2022	1.2