Year	Number of
1990	121.62
1991	126.2
1992	131.21
1993	136.7
1994	142.38
1995	148.19
1996	151.92
1997	155.85
1998	158.88
1999	160.8
2000	163.21
2001	164.93
2002	166
2003	168.19
2004	170.68
2005	174.22
2006	177.12
2007	180.59
2008	183.81
2009	188.82
2010	193.02
2011	198.71
2012	205.52
2013	212.69
2014	220.58
2015	228.69
2016	237.09