Year	Number of
1990	150.49
1991	154.66
1992	159.08
1993	163.79
1994	168.79
1995	174.12
1996	181.75
1997	189.86
1998	198.52
1999	207.73
2000	217.56
2001	223.48
2002	229.66
2003	236.19
2004	243.15
2005	250.66
2006	254.81
2007	259.28
2008	264.36
2009	269.84
2010	275.81
2011	282.6
2012	289.96
2013	297.57
2014	305.75
2015	314.51
2016	324.62