Year Number 1960 0 1965 0 1970 0 1975 0 1976 0 1977 0 1978 0 1979 0 1980 0 1981 0 1982 0 1983 0 1984 0 1985 0 1986 0 1987 0 1988 0 1989 0 1990 0 1991 0 1992 0 1993 0 1994 0 1995 0 1996 61 1997 300 1998 297 1999 600 2000 5000 2001 15000 2002 32000 2003 41500 2004 61900 2005 96900 2006 120000 2007 150000 2008 180000 2009 200000 2010 399290 2011 478860 2012 501077 2013 510783 2014 516540 2015 533336 2016 575650 2017 566113 2018 591223 2019 617000 2020 744081 2021 816689 2022 893441