Year	Number of
1990	102.71
1991	103.74
1992	104.86
1993	106.88
1994	108.1
1995	109.77
1996	110.42
1997	112.16
1998	114.35
1999	116.09
2000	119.12
2001	118.39
2002	119
2003	119.4
2004	120.43
2005	122.12
2006	124.96
2007	128.83
2008	132.84
2009	137.55
2010	142.69
2011	147.64
2012	152.89
2013	158.3
2014	164.12
2015	170.56
2016	177.32