Year	per 1,000
1990	1.243090176534738
1991	1.2095838494622912
1992	1.2631733001883798
1993	1.2102865254852013
1994	1.0831626657793592
1995	1.09011978087791
1996	1.0222441063991234
1997	0.9473127702787503
1998	0.9128424557648067
1999	0.8589602141874263
2000	0.8237978610321537
2001	0.7992430778284748
2002	0.7834738865939259
2003	0.7133401185648148
2004	0.6790552621063418
2005	0.6591926134297985
2006	0.652077140921827
2007	0.6382789823529952
2008	0.5898381648631801
2009	0.5646969079492798
2010	0.5537320116557078
2011	0.5964974106380458
2012	0.521217334201466
2013	0.5197958249043028
2014	0.5117291220126998
2015	0.5057249248567671
2016	0.49900547267956563
2017	0.49297551889476454
2018	0.47651665491235246
2019	0.4760906513805097
2020	0.46604190588909544
2021	0.4597219095429078
2022	0.4726426515459609