Year	Number of
1990	90.05
1991	94.78
1992	103.02
1993	111.67
1994	119.72
1995	126.88
1996	132.83
1997	136.3
1998	141.03
1999	142.92
2000	145.36
2001	148.72
2002	154.7
2003	161.22
2004	164.65
2005	166.96
2006	168.35
2007	171.99
2008	175.57
2009	180.46
2010	187.54
2011	193.71
2012	201.33
2013	209.91
2014	217.14
2015	223.41
2016	229.01