Year	Number
1993	22.95133
1994	24.23755
1995	23.84921
1996	25.29659
1997	24.88869
1998	24.52423
1999	24.66267
2000	24.48359
2001	24.69098
2002	24.58673
2003	24.6366
2004	24.82346
2005	24.07453
2006	23.65864
2007	23.38092
2008	22.82817
2009	22.31924
2010	22.32122
2011	23.26631
2012	23.6921
2013	22.49587
2014	22.63819
2015	22.49472
2016	21.50171
2017	21.14073
2018	21.32611