Year	Number of
1990	120.1
1991	122.25
1992	124.51
1993	126.73
1994	128.95
1995	131.21
1996	131.2
1997	131.06
1998	131.12
1999	131.47
2000	132.24
2001	130.95
2002	130.39
2003	130.57
2004	131.17
2005	132.08
2006	133.76
2007	135.65
2008	137.67
2009	139.87
2010	142.33
2011	146.66
2012	151.38
2013	156.15
2014	161.28
2015	166.79
2016	172.87