Year	Number
1987	0.3270708146
1988	0.3305814137
1989	0.3340920128
1990	0.3376026119
1991	0.341113211
1992	0.3446238101
1993	0.3481344091
1994	0.3516450082
1995	0.3551556073
1996	0.3586662064
1997	0.3621768055
1998	0.3656874046
1999	0.3691980036
2000	0.3727086027
2001	0.4997222549
2002	0.626735907
2003	0.7537495592
2004	0.8807632113
2005	1.0077768635
2006	1.1347905156
2007	1.2618041678
2008	1.3888178199
2009	1.5049924974
2010	1.6211671749
2011	1.7135087853
2012	1.835399711
2013	1.835399711
2014	1.835399711
2015	1.835399711
2016	1.835399711
2017	1.835399711
2018	1.835399711
2019	1.835399711
2020	1.835399711