Year	Number of
1990	323.62
1991	316.53
1992	319.02
1993	313.98
1994	310.17
1995	306.75
1996	299.48
1997	300.61
1998	303.22
1999	305.91
2000	309.91
2001	310.53
2002	318.51
2003	328.68
2004	343.82
2005	354.69
2006	366.41
2007	372.96
2008	377.68
2009	388.57
2010	405.48
2011	418.85
2012	435.23
2013	450.51
2014	462.89
2015	475.26
2016	489.65