Year	Number of
1990	142.57
1991	147.11
1992	152.4
1993	157.46
1994	162.75
1995	166.08
1996	168.88
1997	170.03
1998	167.63
1999	165.11
2000	159.1
2001	156.31
2002	149.28
2003	147.32
2004	145.08
2005	142.96
2006	139.4
2007	136.83
2008	139.36
2009	141.45
2010	145.21
2011	145.73
2012	151.41
2013	154.58
2014	157.43
2015	159.36
2016	161.63