Year	Number of
1990	321.41
1991	317.63
1992	318.64
1993	320.93
1994	323.35
1995	327.81
1996	325.76
1997	325.43
1998	323.72
1999	331.65
2000	338.74
2001	345.57
2002	358.06
2003	367.29
2004	396.64
2005	402.21
2006	403.51
2007	411.56
2008	420.92
2009	432.44
2010	443.49
2011	453
2012	463.69
2013	474.19
2014	483.44
2015	498.04
2016	514.31