Year	Number of
1990	222.96
1991	232.8
1992	232
1993	234.6
1994	239.48
1995	241.96
1996	242.94
1997	242.41
1998	233.89
1999	233.21
2000	230.23
2001	221.6
2002	217.83
2003	216.65
2004	213.54
2005	201.91
2006	191.14
2007	186.26
2008	179.77
2009	176.35
2010	174.84
2011	172.47
2012	172.3
2013	170.4
2014	164.98
2015	167.74
2016	164.61