Year Number 1970 9529.0322265625 1971 9798.3603515625 1972 10279.6787109375 1973 10109.826171875 1974 10229.177734375 1975 10467.9833984375 1976 10546.7568359375 1977 10593.4736328125 1978 10787.9677734375 1979 10814.8837890625 1980 10851.8427734375 1981 10784.603515625 1982 11036.6279296875 1983 11308.0888671875 1984 11563.65234375 1985 11586.7255859375 1986 12115.5732421875 1987 12337.6064453125 1988 12572.8564453125 1989 12819.53125 1990 12919.501953125 1991 12869.49609375 1992 12981.6826171875 1993 13089.4619140625 1994 13363.6474609375 1995 13791.81640625 1996 13622.6669921875 1997 13965.3525390625 1998 13953.0849609375 1999 13513.0859375 2000 12982.5078125 2001 13417.19140625 2002 13552.31640625 2003 13666.513671875 2004 13952.3955078125 2005 13922.392578125 2006 13857.7265625 2007 13671.779296875 2008 13959.328125 2009 13884.1298828125 2010 14119.474609375 2011 14169.1533203125 2012 14714.896484375 2013 14625.1904296875 2014 15058.408203125 2015 14289.640625 2016 14766.3837890625 2017 15256.8916015625 2018 15770.5048828125 2019 16621.162109375 2020 16531.86328125 2021 16781.50390625