Year	Number of
1990	549.67
1991	580.26
1992	560.21
1993	550.44
1994	544.56
1995	538.57
1996	539.95
1997	536.56
1998	534.1
1999	529.57
2000	520.94
2001	521.69
2002	514.57
2003	515.17
2004	507.03
2005	502.33
2006	498.22
2007	500.54
2008	486.46
2009	484.58
2010	490.73
2011	492.54
2012	493.85
2013	486.75
2014	478.51
2015	479.48
2016	481.84