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 0 1997 0 1998 0 1999 6740 2000 17757 2001 27500 2002 50369 2003 51324 2004 155534 2005 410630 2006 866700 2007 1208498 2008 1954527 2009 4051703 2010 6854000 2011 14126659 2012 20523889 2013 25646865 2014 30490000 2015 42311629 2016 51224000 2017 39600000 2019 41920000 2020 44500000 2021 64500000 2022 69123028