Year Number of 1990 1967.04 1991 2003.35 1992 2071.53 1993 2111.66 1994 2168.52 1995 2234.96 1996 2280.97 1997 2339.18 1998 2383.01 1999 2485.06 2000 2566.48 2001 2615.61 2002 2699.72 2003 2789.34 2004 2886.84 2005 2980.2 2006 3070.05 2007 3167.27 2008 3281.7 2009 3424.17 2010 3577.01 2011 3726.22 2012 3881.85 2013 4024.99 2014 4196.76 2015 4364.7 2016 4557.6