Year	Number of
1990	106.85
1991	107.42
1992	107.98
1993	108.52
1994	109.18
1995	110.1
1996	110.51
1997	111.13
1998	111.83
1999	112.64
2000	113.66
2001	115.06
2002	116.67
2003	118.43
2004	120.35
2005	122.56
2006	125.68
2007	128.83
2008	132.44
2009	136.28
2010	140.53
2011	144.12
2012	148.03
2013	152.23
2014	156.64
2015	161.24
2016	166.28