Year	per 1,000
1990	4.758730415711833
1991	3.8770471785153973
1992	3.6695164991929525
1993	3.519351009144527
1994	3.349142067569233
1995	3.223063529534672
1996	3.1025152846873882
1997	2.9951989972112205
1998	2.9272188003934807
1999	2.8071976382900785
2000	2.738256049469367
2001	2.6685614878702753
2002	2.609110401579827
2003	2.9548767761504187
2004	2.4978964563457353
2005	2.4719505140659956
2006	2.4840006543976227
2007	2.4812142676642472
2008	2.4823223660822604
2009	2.488573347892493
2010	2.452156942571451
2011	2.502138670218296
2012	2.7020691408973567
2013	2.698756815982308
2014	2.6328989082387637
2015	2.588658356938646
2016	2.4080237744923982
2017	2.4202774563468172
2018	2.397644356507046
2019	2.188148011264906
2020	2.0924256775525656
2021	2.048064439423045
2022	1.980441817224681