Year	Number of
1990	109.16
1991	107.56
1992	106.13
1993	104.6
1994	103.12
1995	101.66
1996	99.87
1997	97.9
1998	96.04
1999	94.37
2000	92.98
2001	96.01
2002	99.55
2003	104.01
2004	108.56
2005	113.13
2006	115.87
2007	118.45
2008	121.28
2009	124.53
2010	128.35
2011	131.95
2012	135.98
2013	140.06
2014	144.22
2015	148.49
2016	152.15