Year Number 1971 24815 1972 24834 1973 24850 1974 25241 1975 25308 1976 26374 1978 28492 1979 26049 1980 26369 1981 27525 1982 27561 1983 27731 1984 27942 1985 28175 1986 32806 1987 33100 1988 33330 1989 33594 1990 33796 1991 34232 1992 34902 1993 33507 1994 32059 1995 32634 1996 30674 1997 31251 1998 31716 1999 28890 2002 29129 2003 28822 2004 28397 2005 29239 2006 29044 2007 29274 2008 29017 2009 29179 2010 29743 2011 29957 2012 30203.90234375 2013 30565.955078125 2014 30533.423828125 2015 30972.43359375 2016 31933.224609375 2017 33438.03125 2019 32234.33984375 2020 32150.228515625 2021 32848.0859375 2022 31243.015625