Year	Number of
1990	205.53
1991	211.47
1992	215.51
1993	222.46
1994	225.72
1995	231.73
1996	234.07
1997	229.12
1998	233.35
1999	232.88
2000	232.94
2001	234.43
2002	231.63
2003	229.17
2004	233.07
2005	231.76
2006	230.27
2007	230.39
2008	239.49
2009	246.49
2010	256.87
2011	263.73
2012	278.64
2013	288.77
2014	299.21
2015	315
2016	328.29