Year	Number of
1990	102.98
1991	104.36
1992	105.96
1993	107.57
1994	109.14
1995	110.77
1996	110.25
1997	109.67
1998	109.17
1999	108.93
2000	109.22
2001	109.16
2002	109.9
2003	111.23
2004	112.89
2005	114.83
2006	117
2007	119.27
2008	121.84
2009	124.67
2010	127.93
2011	131.83
2012	136.2
2013	140.81
2014	145.77
2015	151.07
2016	156.56