Year	Number of
1990	92.38
1991	93.73
1992	95.48
1993	97.21
1994	99.18
1995	101.68
1996	103.28
1997	105.02
1998	108.07
1999	110.39
2000	112.36
2001	111.58
2002	113.99
2003	115.33
2004	118.84
2005	118.32
2006	121.59
2007	124.79
2008	126.67
2009	130.27
2010	131.7
2011	131.81
2012	135
2013	137.72
2014	140.31
2015	143.15
2016	145.88