Year	Number
1994	16.22707
1995	16.57725
1996	15.94392
1997	16.80589
1998	18.4319
1999	17.40195
2000	18.05938
2001	19.22717
2002	19.23637
2003	18.51464
2004	18.68939
2005	18.39796
2006	18.248
2007	17.50397
2008	17.17812
2009	17.15175
2010	17.04874
2011	17.17087
2012	17.38188
2013	19.69174
2014	19.56236
2015	19.09714
2016	18.74818
2017	18.52053
2018	18.4564