Year	per 1,000
1990	1.3
1991	1.3
1992	1.3
1993	1.2
1994	1.2
1995	1.2
1996	1.1
1997	1.1
1998	1.1
1999	1.1
2000	1
2001	1
2002	1
2003	0.9
2004	0.9
2005	0.9
2006	0.8
2007	0.8
2008	0.8
2009	0.8
2010	0.7
2011	0.7
2012	0.7
2013	0.6
2014	0.6
2015	0.6
2016	0.6
2017	0.5
2018	0.5
2019	0.5
2020	0.5
2021	0.5
2022	0.5