Year	Number of
1990	320.55
1991	326.48
1992	333.88
1993	342.17
1994	350.85
1995	360.06
1996	365.7
1997	371.74
1998	378.4
1999	385.96
2000	394.97
2001	405.23
2002	417.3
2003	430.91
2004	445.45
2005	461.08
2006	480.08
2007	499.97
2008	521.73
2009	545.13
2010	570.73
2011	590.36
2012	611.92
2013	634.75
2014	659.08
2015	684.9
2016	711.77