Year	per 1,000
1990	2.6
1991	2.8
1992	31.6
1993	34.6
1994	11.6
1995	5.6
1996	2.2
1997	2
1998	1.8
1999	1.7
2000	1.6
2001	1.5
2002	1.5
2003	1.5
2004	1.5
2005	1.6
2006	1.6
2007	1.6
2008	1.6
2009	1.6
2010	1.5
2011	1.5
2012	1.5
2013	1.5
2014	1.5
2015	1.6
2016	1.6
2017	1.6
2018	1.6
2019	1.5
2020	1.5
2021	1.4
2022	1.4