Year	Number of
1990	289.37
1991	293.98
1992	299.35
1993	305.22
1994	311.53
1995	318.69
1996	317.97
1997	317.91
1998	318.2
1999	318.84
2000	320.26
2001	320.15
2002	320.23
2003	319.93
2004	320.22
2005	321.18
2006	321.09
2007	321.31
2008	321.56
2009	321.5
2010	321.52
2011	322.17
2012	323.24
2013	324.05
2014	325.17
2015	326.7
2016	328.58