Year	Number of
1990	132.08
1991	139.11
1992	146.62
1993	154.78
1994	163.59
1995	173.08
1996	183.44
1997	194.56
1998	206.68
1999	219.48
2000	232.98
2001	246.93
2002	261.68
2003	278.18
2004	295.54
2005	313.88
2006	331.83
2007	350.52
2008	371.18
2009	393.13
2010	416.6
2011	439.32
2012	463.67
2013	490.14
2014	517.92
2015	546.93
2016	577