Year	Number of
1990	90.67
1991	94.62
1992	99.51
1993	105.26
1994	110.21
1995	108.56
1996	113.57
1997	113.73
1998	115.69
1999	116.06
2000	118.19
2001	119.62
2002	121.47
2003	122.8
2004	121.48
2005	122.41
2006	125.74
2007	129.47
2008	132.18
2009	132.65
2010	132.5
2011	133.27
2012	131.17
2013	134.91
2014	139.13
2015	139.52
2016	141.18