| Year | Value | | 2023 | 20,713,050 | | 2022 | 20,641,158 | | 2021 | 20,266,092 | | 2020 | 20,317,415 | | 2019 | 20,706,729 | | 2018 | 20,458,859 | | 2017 | 20,414,168 | | 2016 | 20,276,847 | | 2015 | 19,804,238 | | 2014 | 19,671,986 | | 2013 | 19,536,889 | | 2012 | 19,294,728 | | 2011 | 19,250,536 | | 2010 | 19,277,285 | | 2009 | 19,277,921 | | 2008 | 19,184,794 | | 2007 | 19,174,639 | | 2006 | 19,024,612 | | 2005 | 18,688,032 | | 2004 | 18,040,925 | | 2003 | 18,104,397 | | 2002 | 17,906,251 | | 2001 | 17,809,945 | | 2000 | 17,584,296 | | 1999 | 17,573,637 | | 1998 | 17,346,568 | | 1997 | 17,248,052 | | 1996 | 17,086,499 | | 1995 | 16,972,780 | | 1994 | 16,968,482 | | 1993 | 16,869,563 | | 1992 | 16,881,851 | | 1991 | 16,888,922 |
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