Year	Number of
1990	270.22
1991	282.52
1992	294.77
1993	309.15
1994	322.16
1995	334.98
1996	342.69
1997	349.94
1998	353.7
1999	361.5
2000	369.36
2001	376.24
2002	382.51
2003	388.63
2004	393.97
2005	398.35
2006	401.54
2007	405.29
2008	410.08
2009	416.02
2010	421.96
2011	430.28
2012	440.61
2013	450.04
2014	461.71
2015	479.95
2016	500.71