Year	per 1,000
1990	1.5
1991	1.5
1992	1.5
1993	1.5
1994	1.4
1995	1.4
1996	1.4
1997	1.3
1998	1.3
1999	1.2
2000	1.2
2001	1.1
2002	1.1
2003	1
2004	1
2005	0.9
2006	0.9
2007	0.9
2008	0.9
2009	0.8
2010	0.8
2011	0.8
2012	0.8
2013	0.8
2014	0.8
2015	0.8
2016	0.8
2017	0.8
2018	0.8
2019	0.8
2020	0.8
2021	0.7
2022	0.7