Year	Number
1992	10.2850380022
1993	9.7793485342
1994	9.2736590662
1995	8.7679695983
1996	8.2622801303
1997	7.7565906623
1998	7.2509011944
1999	6.7452117264
2000	6.2395222584
2001	6.1727252986
2002	6.1059283388
2003	6.0391313789
2004	5.9723344191
2005	5.9055374593
2006	5.9163952226
2007	5.9272529859
2008	5.9381107492
2009	5.842487785
2010	5.7468648208
2011	5.6512418567
2012	5.5556188925
2013	5.4599959283
2014	5.3643729642
2015	5.26875
2016	5.1731270358
2017	4.4772964169
2018	4.2056026059
2019	5.1209771987
2020	5.3867100977