Year	Number of
1990	168.19
1991	168.39
1992	171.45
1993	174.87
1994	179.93
1995	182.27
1996	186.21
1997	189.96
1998	195.49
1999	200.37
2000	205.94
2001	211.43
2002	218.9
2003	227.73
2004	231.05
2005	232.04
2006	230.45
2007	228.54
2008	241.76
2009	249.77
2010	256.52
2011	259.32
2012	272.27
2013	271.83
2014	278.59
2015	287.86
2016	294.54