Year	Number of
1990	110.55
1991	113.03
1992	114.45
1993	116.63
1994	118.78
1995	120.55
1996	122.82
1997	123.7
1998	125.7
1999	126.24
2000	125.89
2001	125.33
2002	126.09
2003	126.24
2004	126.73
2005	127.83
2006	130
2007	131.65
2008	133.47
2009	135.34
2010	140.05
2011	142.56
2012	144.41
2013	146.31
2014	148.08
2015	150.37
2016	152.94