Year	Hours
1970-01-01	1930
1971-01-01	1913
1972-01-01	1902
1973-01-01	1898
1974-01-01	1883
1975-01-01	1867
1976-01-01	1838
1977-01-01	1832
1978-01-01	1838
1979-01-01	1834
1980-01-01	1809
1981-01-01	1809
1982-01-01	1788
1983-01-01	1786
1984-01-01	1790
1985-01-01	1799
1986-01-01	1797
1987-01-01	1812
1988-01-01	1830
1989-01-01	1825
1990-01-01	1807
1991-01-01	1783
1992-01-01	1782
1993-01-01	1808
1994-01-01	1825
1995-01-01	1815
1996-01-01	1831
1997-01-01	1814
1998-01-01	1809
1999-01-01	1810
2000-01-01	1802
2001-01-01	1791
2002-01-01	1771
2003-01-01	1756
2004-01-01	1774
2005-01-01	1763
2006-01-01	1760
2007-01-01	1756
2008-01-01	1746
2009-01-01	1715
2010-01-01	1724
2011-01-01	1724