Year	Number
1993	23.58827
1994	24.99819
1995	24.6472
1996	26.41142
1997	26.26352
1998	25.63624
1999	26.08822
2000	26.16809
2001	25.86923
2002	25.79843
2003	25.89807
2004	26.24101
2005	25.12596
2006	24.44171
2007	24.00443
2008	23.18095
2009	22.29256
2010	23.10328
2011	23.60768
2012	24.04289
2013	22.29867
2014	22.44913
2015	22.28691
2016	21.21287
2017	20.96896
2018	21.21797