Year	Number
1987	4.9329608939
1988	4.9997717018
1989	5.0665825097
1990	5.1333933176
1991	5.2002041255
1992	5.2670149334
1993	5.333366459
1994	5.4001007198
1995	5.4674473571
1996	5.534258165
1997	5.6003035024
1998	5.6670377632
1999	5.7337720241
2000	5.8015013966
2001	5.8015013966
2002	5.8015013966
2003	5.8015013966
2004	5.8015013966
2005	5.8015013966
2006	5.8015013966
2007	5.8015013966
2008	5.8015013966
2009	5.8015013966
2010	5.8015013966
2011	5.8015013966
2012	5.8015013966
2013	5.8015013966
2014	5.8015013966
2015	5.8015013966
2016	5.8015013966
2017	5.8015013966
2018	5.8015013966
2019	5.8015013966
2020	5.8015013966