Year	Number
1994	22.2759
1995	22.42283
1996	22.86531
1997	23.52736
1998	22.87925
1999	22.38191
2000	20.63497
2001	18.99521
2002	16.27823
2003	15.85783
2004	15.6855
2005	15.83024
2006	15.67192
2007	16.04109
2008	16.27768
2009	16.52448
2010	16.24442
2011	14.72249
2012	14.86215
2013	14.63593
2014	14.16183
2015	13.85511
2016	13.58391
2017	13.03311