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