Year	Number
1982	19.86947
1994	14.26627
1996	15.66631
1997	15.17959
1998	17.42447
1999	15.3898
2000	15.54971
2001	15.03428
2003	14.1861
2004	13.17799
2005	14.71095
2006	14.70968
2007	14.63451
2008	14.4931
2009	14.30599
2010	14.50074
2011	14.36822
2012	14.36042
2014	13.96236
2015	13.81545
2016	13.8189
2017	13.62875