Year	Number
1983	0.905919098511119
1984	0.7503128660981088
1985	0.7035229077121552
1986	0.6481358385982752
1987	0.49024342582891584
1988	0.543491676429524
1989	0.6684950812864286
1990	0.6938023897467984
1991	0.6067778683165619
1992	0.7193535837328602
1993	0.6501297053114498
1994	0.6288903274908902
1995	0.7679721165461391
1996	0.5255661891775076
1997	0.8209485548313328
1998	0.6050096380580746
1999	0.6726299413026968
2000	0.69600439376781
2001	0.7022775639177685
2002	0.8888104116987944
2003	0.9436479022302898
2004	1.0363786335328413
2005	1.0261695450406756
2006	1.0159342203624764
2007	0.970656852307233
2008	1.063903680475861
2009	1.0330209894791778
2010	1.1339651352297317
2011	1.4718695409514346
2012	1.1248301742846738
2013	1.0248774839217505
2014	0.9865055276152338
2015	1.1003872053356503
2016	1.2700465946407795
2017	1.436913963007521
2018	1.781265082549132
2019	1.5504690050177687
2020	1.6368693624046642
2021	2.4751861917977207