Year	Number of
1990	570.06
1991	572.35
1992	573.4
1993	573.95
1994	573.73
1995	573.27
1996	548.92
1997	525.01
1998	500.96
1999	477.24
2000	454.06
2001	462.42
2002	469.85
2003	475.95
2004	481.56
2005	487.14
2006	489.73
2007	492.54
2008	496.35
2009	500.63
2010	505.51
2011	516.64
2012	529.34
2013	542.95
2014	557.7
2015	573.54
2016	592.2