Year	Number of
1990	108.05
1991	110.55
1992	112.47
1993	116.25
1994	119.62
1995	122.98
1996	126.55
1997	130
1998	133.02
1999	134.52
2000	136.63
2001	131.89
2002	130.77
2003	131.09
2004	131.8
2005	133.41
2006	136.67
2007	140.59
2008	145.55
2009	149.94
2010	153.78
2011	152.28
2012	150.13
2013	146.58
2014	143.21
2015	141.25
2016	142.95