Year	per 1,000
1990	7.9
1991	7.8
1992	7.7
1993	7.6
1994	7.4
1995	7.3
1996	7.2
1997	7.1
1998	7
1999	6.8
2000	6.7
2001	6.6
2002	6.6
2003	6.5
2004	6.5
2005	6.5
2006	6.5
2007	6.5
2008	6.5
2009	6.5
2010	6.5
2011	6.5
2012	6.5
2013	6.5
2014	6.4
2015	6.4
2016	6.4
2017	6.4
2018	6.4
2019	6.5
2020	6.5
2021	6.5
2022	7.2