Year	per 1,000
1990	1.3
1991	1.3
1992	1.3
1993	1.3
1994	1.3
1995	1.2
1996	1.2
1997	1.2
1998	1.2
1999	1.1
2000	1.1
2001	1.1
2002	1
2003	1
2004	1
2005	1
2006	0.9
2007	0.9
2008	0.9
2009	0.8
2010	0.8
2011	0.8
2012	0.8
2013	0.7
2014	0.7
2015	0.7
2016	0.7
2017	0.6
2018	0.6
2019	0.6
2020	0.6
2021	0.6
2022	0.6