Year	Number
1994	16.32209
1995	17.3118
1996	17.90984
1997	18.27792
1998	18.34543
1999	18.33527
2000	18.60083
2001	19.25426
2002	19.11022
2003	20.00424
2004	19.49373
2005	18.58831
2006	17.60414
2007	17.13937
2008	16.44409
2009	16.19875
2010	15.71961
2011	15.62857
2012	15.40634
2013	14.87017
2014	14.47108
2015	14.27734
2016	13.99937
2017	14.33777
2018	14.41867