Year	Hours
1980-01-01	2811
1981-01-01	2795
1982-01-01	2915
1983-01-01	2889
1984-01-01	2873
1985-01-01	2873
1986-01-01	2811
1987-01-01	2889
1988-01-01	2910
1989-01-01	2842
1990-01-01	2805
1991-01-01	2784
1992-01-01	2738
1993-01-01	2748
1994-01-01	2732
1995-01-01	2738
1996-01-01	2727
1997-01-01	2680
1998-01-01	2612
1999-01-01	2628
2000-01-01	2638
2001-01-01	2628
2002-01-01	2597
2003-01-01	2560
2004-01-01	2539
2005-01-01	2508
2006-01-01	2498
2007-01-01	2456
2008-01-01	2399
2009-01-01	2393
2010-01-01	2352
2011-01-01	2289