Year	Number of
1990	111.85
1991	114.25
1992	117.07
1993	120.93
1994	122.7
1995	125.15
1996	124.45
1997	125.61
1998	126.18
1999	126.08
2000	127.48
2001	129.1
2002	130.24
2003	130.78
2004	132.97
2005	134.46
2006	135.97
2007	137.74
2008	138.97
2009	141.29
2010	141.97
2011	143.32
2012	144.49
2013	146.76
2014	148.47
2015	151.39
2016	154.54