Year	per 1,000
1990	3.3
1991	4.6
1992	8.3
1993	12.4
1994	10.9
1995	6.6
1996	4.4
1997	4
1998	4.1
1999	3.8
2000	3.2
2001	2.8
2002	2.7
2003	2.7
2004	2.8
2005	2.8
2006	2.8
2007	2.7
2008	2.9
2009	2.7
2010	2.7
2011	2.7
2012	2.8
2013	2.7
2014	2.7
2015	2.7
2016	2.7
2017	2.5
2018	2.5
2019	2.7
2020	5.5
2021	3.3
2022	3