Year	Number
1991	9.0446741739
1992	9.7477847517
1993	10.4508953295
1994	11.1540059073
1995	11.8571164851
1996	11.9661647195
1997	12.0752129539
1998	12.1842611883
1999	12.2933094227
2000	12.4023576571
2001	12.5114058915
2002	12.6204541259
2003	12.7295023603
2004	12.8385505947
2005	12.9475988291
2006	13.0566470635
2007	13.1656952979
2008	13.2747435323
2009	13.3837917667
2010	13.3837917667
2011	13.3837917667
2012	13.3837917667
2013	13.3837917667
2014	13.3837917667
2015	13.3837917667
2016	13.3837917667
2017	13.3837917667
2018	13.3837917667
2019	13.3837917667
2020	13.3837917667