Year	Number of
1990	252.9
1991	243
1992	240.42
1993	234.36
1994	235.71
1995	237.33
1996	239.97
1997	240.37
1998	235.82
1999	233.72
2000	227.04
2001	224.52
2002	226.69
2003	229.3
2004	234.14
2005	232.81
2006	239.7
2007	233.23
2008	231.83
2009	243.26
2010	242.94
2011	251.68
2012	240.43
2013	236.43
2014	231.38
2015	228.68
2016	238.78