Year	per 1,000
1990	4.1426640390120975
1991	3.979113943885521
1992	3.8911884060824895
1993	3.7972461536937594
1994	3.6768684053787823
1995	3.623544999891863
1996	3.5471090527381173
1997	3.4302732744806703
1998	3.3588265309253886
1999	3.3276434667514003
2000	3.206457681581493
2001	3.1438806063337426
2002	3.0963919685670023
2003	3.0865114051445515
2004	3.1282238088455934
2005	2.939970065821667
2006	2.90433479871551
2007	2.8442916256293933
2008	2.8238950219380947
2009	2.7162908657250804
2010	2.614936562222108
2011	2.5380172110260903
2012	2.482401320289186
2013	2.3831725186775605
2014	2.281701869896081
2015	2.2301358884978475
2016	2.1401424725826104
2017	2.0644321143224857
2018	1.9748729973781172
2019	1.9143951945463744
2020	1.8678457996328846
2021	1.7907402939852346
2022	1.7242812009271409