Year Number of 1990 3524.6 1991 3754.32 1992 4036.62 1993 4282.02 1994 4569.57 1995 4887.32 1996 5099.58 1997 5299.24 1998 5566.89 1999 5860.45 2000 6126.33 2001 6356.53 2002 6574.46 2003 6769.78 2004 6949.36 2005 7099.71 2006 7151.86 2007 7265.02 2008 7367.99 2009 7498.91 2010 7625.86 2011 7776.35 2012 7916.94 2013 8166.85 2014 8411.26 2015 8669.11 2016 8950.15