Year	Number
1994	16.35923
1995	17.33619
1996	17.92578
1997	18.28883
1998	18.35513
1999	18.34508
2000	18.60721
2001	19.25282
2002	19.11028
2003	19.9937
2004	19.48908
2005	18.59395
2006	17.62067
2007	17.16091
2008	16.47289
2009	16.23668
2010	15.75505
2011	15.66505
2012	15.44524
2013	14.914
2014	14.51876
2015	14.32573
2016	14.04987
2017	14.38457
2018	14.45427