Year	Number of
1990	99.05
1991	99.36
1992	100
1993	101.56
1994	103.32
1995	104.09
1996	105.37
1997	106.67
1998	109.41
1999	108.91
2000	111.77
2001	115.76
2002	118.59
2003	127.85
2004	129.71
2005	134.98
2006	138.7
2007	144.25
2008	152.66
2009	154.71
2010	158.94
2011	160.59
2012	163.55
2013	167.51
2014	171.21
2015	174.71
2016	178.78