| Year | Value | | 2024 | 21,532,540 | | 2023 | 20,924,078 | | 2022 | 20,475,675 | | 2021 | 20,186,456 | | 2020 | 19,725,450 | | 2019 | 19,119,647 | | 2018 | 18,564,622 | | 2017 | 18,038,999 | | 2016 | 17,541,315 | | 2015 | 17,099,520 | | 2014 | 16,570,680 | | 2013 | 15,974,952 | | 2012 | 15,432,887 | | 2011 | 14,815,166 | | 2010 | 14,272,310 | | 2009 | 13,853,158 | | 2008 | 13,350,888 | | 2007 | 13,056,363 | | 2006 | 12,805,479 | | 2005 | 12,284,658 | | 2004 | 11,851,534 | | 2003 | 11,426,685 | | 2002 | 10,737,198 | | 2001 | 10,179,793 | | 2000 | 10,094,645 | | 1999 | 9,964,825 | | 1998 | 9,593,052 | | 1997 | 9,232,074 | | 1996 | 8,880,573 | | 1995 | 8,525,665 | | 1994 | 8,113,904 | | 1993 | 7,456,723 | | 1992 | 6,624,209 | | 1991 | 6,106,550 | | 1990 | 6,011,167 | | 1989 | 5,926,628 | | 1988 | 5,753,395 | | 1987 | 5,691,607 | | 1986 | 5,717,133 | | 1985 | 5,736,473 | | 1984 | 5,639,756 | | 1983 | 5,520,174 | | 1982 | 5,570,563 | | 1981 | 6,062,427 | | 1980 | 6,697,575 | | 1979 | 6,954,359 | | 1978 | 6,939,643 | | 1977 | 6,806,361 | | 1976 | 6,666,595 |
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