Year	Number of
1990	169.17
1991	156.74
1992	150.42
1993	145.93
1994	139.37
1995	133.43
1996	129.59
1997	126.08
1998	120.48
1999	122.02
2000	123.61
2001	127.65
2002	133.02
2003	139.48
2004	149.27
2005	157.21
2006	160.81
2007	164.46
2008	166.67
2009	169.86
2010	175.71
2011	184.44
2012	194.53
2013	207.98
2014	220.92
2015	231.8
2016	244.63