Year	Number of
1990	307.16
1991	309.6
1992	311.96
1993	314.48
1994	317.7
1995	321.65
1996	324.26
1997	326.98
1998	329.87
1999	333.35
2000	334.89
2001	335.93
2002	340.24
2003	344.61
2004	349.43
2005	355.89
2006	363.82
2007	371.69
2008	380.61
2009	390.46
2010	401.37
2011	413.42
2012	425.88
2013	439.78
2014	455.67
2015	470.95
2016	486.63