Year	Number of
1990	105.11
1991	108.81
1992	112.94
1993	118.1
1994	123.55
1995	129.38
1996	135.49
1997	141.63
1998	147.93
1999	152.75
2000	162.2
2001	159.2
2002	159.07
2003	162.59
2004	162.95
2005	165.83
2006	173.95
2007	187.48
2008	206.07
2009	225.43
2010	246.5
2011	249.54
2012	250.04
2013	249.29
2014	249.6
2015	252.89
2016	256.24