| Year | Value | | 2023 | 28,965 | | 2022 | 28,448 | | 2021 | 27,664 | | 2020 | 26,874 | | 2019 | 26,647 | | 2018 | 26,330 | | 2017 | 25,935 | | 2016 | 25,601 | | 2015 | 25,400 | | 2014 | 25,148 | | 2013 | 24,804 | | 2012 | 24,440 | | 2011 | 24,024 | | 2010 | 23,776 | | 2009 | 23,466 | | 2008 | 23,061 | | 2007 | 22,762 | | 2006 | 22,539 | | 2005 | 22,288 | | 2004 | 22,148 | | 2003 | 22,035 | | 2002 | 21,919 | | 2001 | 21,832 | | 2000 | 21,805 | | 1999 | 21,751 | | 1998 | 21,593 | | 1997 | 21,426 | | 1996 | 21,210 | | 1995 | 21,133 | | 1994 | 21,027 | | 1993 | 20,667 | | 1992 | 20,473 | | 1991 | 20,234 |
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