| Year | Value | | 2024 | 18,623,232 | | 2023 | 18,676,092 | | 2022 | 18,681,769 | | 2021 | 18,458,117 | | 2020 | 18,310,914 | | 2019 | 18,113,278 | | 2018 | 18,177,196 | | 2017 | 17,953,001 | | 2016 | 18,021,265 | | 2015 | 18,110,681 | | 2014 | 18,049,508 | | 2013 | 17,958,715 | | 2012 | 18,695,260 | | 2011 | 18,670,801 | | 2010 | 17,844,596 | | 2009 | 17,896,125 | | 2008 | 17,729,248 | | 2007 | 17,488,996 | | 2006 | 17,124,130 | | 2005 | 17,148,383 | | 2004 | 16,807,894 | | 2003 | 16,619,013 | | 2002 | 16,401,505 | | 2001 | 16,178,115 | | 2000 | 15,981,037 | | 1999 | 15,576,477 | | 1998 | 15,531,344 | | 1997 | 15,514,232 | | 1996 | 15,139,096 | | 1995 | 14,589,241 | | 1994 | 14,031,601 | | 1993 | 13,734,104 | | 1992 | 13,425,191 | | 1991 | 13,105,961 | | 1990 | 12,780,542 |
|