Year	Number of
1990	130.49
1991	131.98
1992	134.32
1993	137.58
1994	139.02
1995	140.67
1996	140.38
1997	140.48
1998	141.68
1999	143.36
2000	146.56
2001	143.46
2002	141.26
2003	139.36
2004	137.49
2005	141.37
2006	143.7
2007	145.96
2008	148.34
2009	150.72
2010	152.81
2011	154.17
2012	155.32
2013	156.54
2014	157.84
2015	159.33
2016	160.39