Year	per 1,000
1990	3.7602521538583886
1991	3.740822056934612
1992	3.6501231273849286
1993	3.6033049530892822
1994	3.5290277322878527
1995	3.5716551407685877
1996	3.443461285323835
1997	3.3819893719128222
1998	3.3030745793740337
1999	3.237523556146768
2000	3.2136788002815697
2001	3.12766436183442
2002	3.07131895486429
2003	3.013075145182279
2004	3.023049278052878
2005	2.9384111757097346
2006	2.88457411019299
2007	2.8396862168812675
2008	2.8267464172350794
2009	2.7791886916051514
2010	2.7303900451983707
2011	2.7169469770075967
2012	2.6969478266378943
2013	2.652440114300457
2014	2.5903107460391275
2015	2.533707778844834
2016	2.4653621050389916
2017	2.387841052215068
2018	2.317844656503335
2019	2.2332145067125833
2020	2.1587198602827415
2021	2.09122730935854
2022	2.0208454509983307