Year	Number of
1990	106.19
1991	108.98
1992	112.06
1993	115.29
1994	118.83
1995	122.62
1996	123.28
1997	124.2
1998	125.01
1999	126
2000	127.3
2001	129.47
2002	132.09
2003	134.9
2004	137.84
2005	140.82
2006	143.51
2007	146.12
2008	148.94
2009	151.84
2010	154.91
2011	157.29
2012	159.95
2013	162.7
2014	165.68
2015	168.7
2016	171.92