Year	Number of
1990	135.89
1991	137.23
1992	138.76
1993	138.23
1994	142.37
1995	140.4
1996	140.55
1997	140.73
1998	142.76
1999	151.01
2000	155.95
2001	162.13
2002	166.87
2003	172.25
2004	179.93
2005	187.39
2006	194.09
2007	200.92
2008	209.16
2009	217.04
2010	224.56
2011	231.47
2012	238.34
2013	245.17
2014	251.99
2015	259.4
2016	266.93