Year	Number of
1990	372.53
1991	386.06
1992	401.96
1993	414.18
1994	424.15
1995	434.48
1996	426.22
1997	421.08
1998	417.54
1999	413.7
2000	408.34
2001	426.85
2002	447.55
2003	469.97
2004	492.1
2005	514.7
2006	519.87
2007	525.49
2008	530.1
2009	534.26
2010	538.25
2011	535.11
2012	533.64
2013	533.03
2014	533.51
2015	534.32
2016	535.58