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 2995 1998 7500 1999 17000 2000 50000 2001 95000 2002 165138 2003 243613 2004 332565 2005 433635 2006 708000 2007 1190319 2008 1549542 2009 2187334 2010 2602283 2011 2695335 2012 3312239 2013 4262993 2014 4516114 2015 4855206 2016 5505424 2017 6069905 2018 6144507 2019 6239183 2020 6516510 2021 6254789 2022 6564132