Year	Number of
1990	107.44
1991	109.13
1992	110.53
1993	112.17
1994	113.15
1995	115.15
1996	115.84
1997	116.91
1998	117.71
1999	118.9
2000	120.49
2001	121.75
2002	123.4
2003	125.89
2004	128.52
2005	131.35
2006	135.02
2007	138.7
2008	143.14
2009	147.91
2010	152.67
2011	157.24
2012	162.25
2013	167.26
2014	172.43
2015	177.97
2016	183.71