Year	Number of
1990	72.46
1991	75.81
1992	79.45
1993	82.85
1994	86.34
1995	90.35
1996	92.72
1997	95.12
1998	97.91
1999	101.53
2000	105.23
2001	109.85
2002	114.7
2003	120.26
2004	125.95
2005	131.93
2006	136.28
2007	140.9
2008	146.01
2009	151.31
2010	156.77
2011	161.31
2012	166.32
2013	171.51
2014	177.21
2015	183.34
2016	189.26