Year	per 1,000
1990	3.504089797717231
1991	3.482031141067566
1992	3.415482479294822
1993	3.3667781757164064
1994	3.3058583886108748
1995	3.3152657731526576
1996	3.2175258121977457
1997	3.164055699228733
1998	3.0940103603626254
1999	3.037187938817777
2000	3.0136010429151674
2001	2.94211913592914
2002	2.9041237238520132
2003	2.835511345322791
2004	2.8344284405721005
2005	2.7625826878702764
2006	2.7211318252994814
2007	2.694114144411595
2008	2.662686121939569
2009	2.6564086663860964
2010	2.5733098902522498
2011	2.558999392538272
2012	2.534238982587645
2013	2.4908831775409155
2014	2.4459966288447577
2015	2.4010203266852814
2016	2.3601064344878333
2017	2.3015055247177485
2018	2.2399255011039356
2019	2.238027800619612
2020	2.133950786225363
2021	2.066042428693533
2022	2.0113196639427127