Year	per 1,000
1990	8.925850866438605
1991	9.041277223100424
1992	9.094060467906026
1993	9.101115803136228
1994	9.08826536928676
1995	9.076124417390792
1996	8.90777885829806
1997	8.784030321902119
1998	8.619180432396702
1999	8.418066038059527
2000	8.218494475292644
2001	8.060210567396258
2002	7.906666824474911
2003	7.744986685269045
2004	7.603383055098146
2005	7.409927586176634
2006	7.268443561723984
2007	7.122229652204975
2008	7.007765349953025
2009	6.9623354950490635
2010	6.883704808027095
2011	6.874024618829568
2012	6.900448081080742
2013	6.942511422599792
2014	7.005760121575713
2015	7.056890247728702
2016	7.099479776311912
2017	7.088186936238535
2018	7.05721891517503
2019	7.071741904082937
2020	7.028295998335531
2021	7.03989379480815
2022	7.014916588896722