Year	Number of
1990	81.98
1991	86.84
1992	91.76
1993	97.1
1994	102.15
1995	106.34
1996	109.74
1997	112.1
1998	113.38
1999	115.01
2000	118.38
2001	120.77
2002	121.26
2003	124.62
2004	127
2005	128.44
2006	129.66
2007	131.78
2008	134.27
2009	139.34
2010	143.25
2011	147.01
2012	149.91
2013	153.87
2014	158.28
2015	161.92
2016	164.84