Year	per 1,000
1990	4.79013120872364
1991	4.782355246923556
1992	4.705399225534849
1993	4.718220755902641
1994	4.740885490309171
1995	4.703864835026912
1996	4.723837073277443
1997	4.655261709484591
1998	4.6630356336743235
1999	4.589039502425453
2000	4.580695997778558
2001	4.570737683745459
2002	4.468972704597783
2003	4.426565588978723
2004	4.628730841213942
2005	4.263222241647473
2006	4.135334539425132
2007	4.072826167689528
2008	4.101932571493155
2009	3.878177157441835
2010	3.760981684831561
2011	3.7307267656001444
2012	3.654130340636525
2013	3.6538359888617187
2014	3.6678403053394497
2015	3.626800729621889
2016	3.6538897968951005
2017	3.6644369437951663
2018	3.6608803336255127
2019	3.5964291166869873
2020	3.5869454256574422
2021	3.595679567548983
2022	3.5874634102805656