Year	per 1,000
1990	9.160633694777921
1991	9.36454339996542
1992	9.451402110762338
1993	9.471997944209074
1994	9.452308453592085
1995	9.413766901874391
1996	9.157777514143385
1997	8.961052983472724
1998	8.742390643082258
1999	8.48466619221191
2000	8.250554511592666
2001	8.076715262117352
2002	7.895499984011405
2003	7.711904903898151
2004	7.549714653630525
2005	7.313782976820667
2006	7.151697967705228
2007	6.979117919002748
2008	6.851014185025691
2009	6.769700842724208
2010	6.696488926074965
2011	6.6885866470135005
2012	6.725283261911938
2013	6.795656257440548
2014	6.923781370911476
2015	7.0352140943021055
2016	7.156389155425444
2017	7.1965344144668
2018	7.225674805678515
2019	7.250754366255852
2020	7.313939281089295
2021	7.395306952399482
2022	7.416919093432466