Year Number of 1990 2151.56 1991 2282.23 1992 2418.44 1993 2564.12 1994 2724.65 1995 2906.67 1996 2950.83 1997 3008.67 1998 3079.82 1999 3151.3 2000 3222.99 2001 3290.75 2002 3359.29 2003 3446.09 2004 3534.64 2005 3628.61 2006 3736.76 2007 3849.14 2008 3988.52 2009 4136.26 2010 4292.85 2011 4542.87 2012 4813 2013 5114.17 2014 5429.72 2015 5760.73 2016 6111.39