Year	Number
1994	17.61269
1995	17.48272
1996	17.7198
1997	17.52566
1998	18.36794
1999	18.42149
2000	18.59475
2001	18.58743
2002	18.67671
2003	19.11809
2004	19.94793
2005	19.67936
2006	19.74831
2007	19.78008
2008	19.89276
2009	19.39411
2010	19.31061
2011	18.95022
2012	19.00555
2013	19.17939
2014	19.59002
2015	20.03341
2017	19.65558