Year	Hours
1970-01-01	1912
1971-01-01	1896
1972-01-01	1893
1973-01-01	1891
1974-01-01	1863
1975-01-01	1830
1976-01-01	1824
1977-01-01	1823
1978-01-01	1830
1979-01-01	1829
1980-01-01	1815
1981-01-01	1798
1982-01-01	1786
1983-01-01	1795
1984-01-01	1811
1985-01-01	1816
1986-01-01	1797
1987-01-01	1800
1988-01-01	1814
1989-01-01	1828
1990-01-01	1809
1991-01-01	1801
1992-01-01	1793
1993-01-01	1810
1994-01-01	1827
1995-01-01	1846
1996-01-01	1843
1997-01-01	1857
1998-01-01	1870
1999-01-01	1878
2000-01-01	1857
2001-01-01	1833
2002-01-01	1814
2003-01-01	1787
2004-01-01	1787
2005-01-01	1784
2006-01-01	1784
2007-01-01	1776
2008-01-01	1765
2009-01-01	1732
2010-01-01	1742
2011-01-01	1758