Month Hours 1987-01-01 29720000 1987-02-01 34300000 1987-03-01 33560000 1987-04-01 31280000 1987-05-01 31280000 1987-06-01 31180000 1987-07-01 11510000 1987-08-01 31500000 1987-09-01 34130000 1987-10-01 33810000 1987-11-01 34590000 1987-12-01 29130000 1988-01-01 29820000 1988-02-01 33870000 1988-03-01 33080000 1988-04-01 31680000 1988-05-01 31780000 1988-06-01 31420000 1988-07-01 13710000 1988-08-01 31790000 1988-09-01 32960000 1988-10-01 33910000 1988-11-01 35590000 1988-12-01 28540000 1989-01-01 30450000 1989-02-01 34990000 1989-03-01 33340000 1989-04-01 30570000 1989-05-01 31800000 1989-06-01 32540000 1989-07-01 12310000 1989-08-01 32980000 1989-09-01 34180000 1989-10-01 32680000 1989-11-01 35410000 1989-12-01 29520000 1990-01-01 30090000 1990-02-01 33930000 1990-03-01 33190000 1990-04-01 30320000 1990-05-01 30300000 1990-06-01 31610000 1990-07-01 11570000 1990-08-01 32810000 1990-09-01 33210000 1990-10-01 32430000 1990-11-01 33280000 1990-12-01 27530000 1991-01-01 29420000 1991-02-01 31900000 1991-03-01 31260000 1991-04-01 29480000 1991-05-01 28420000 1991-06-01 28860000 1991-07-01 10340000 1991-08-01 30010000 1991-09-01 29950000 1991-10-01 30450000 1991-11-01 30920000 1991-12-01 25120000 1992-01-01 27210000 1992-02-01 29170000 1992-03-01 29160000 1992-04-01 27110000 1992-05-01 26220000 1992-06-01 27210000 1992-07-01 8790000 1992-08-01 26850000 1992-09-01 29070000 1992-10-01 28460000 1992-11-01 29030000 1992-12-01 23490000 1993-01-01 24320000 1993-02-01 26390000 1993-03-01 26930000 1993-04-01 24020000 1993-05-01 25170000 1993-06-01 24960000 1993-07-01 10820000 1993-08-01 24100000 1993-09-01 27490000 1993-10-01 27010000 1993-11-01 27140000 1993-12-01 22670000 1994-01-01 23900000 1994-02-01 26400000 1994-03-01 24830000 1994-04-01 25890000 1994-05-01 23780000 1994-06-01 25870000 1994-07-01 11810000 1994-08-01 24320000 1994-09-01 27080000 1994-10-01 28710000 1994-11-01 28450000 1994-12-01 24340000 1995-01-01 26660000 1995-02-01 27990000 1995-03-01 27440000 1995-04-01 25850000 1995-05-01 25270000 1995-06-01 26150000 1995-07-01 13270000 1995-08-01 25170000 1995-09-01 28980000 1995-10-01 30550000 1995-11-01 30070000 1995-12-01 25000000 1996-01-01 27370000 1996-02-01 29110000 1996-03-01 28520000 1996-04-01 26630000 1996-05-01 25500000 1996-06-01 27280000 1996-07-01 13720000 1996-08-01 23740000 1996-09-01 28090000 1996-10-01 29630000 1996-11-01 29550000 1996-12-01 24870000 1997-01-01 22500000 1997-02-01 28290000 1997-03-01 27820000 1997-04-01 28110000 1997-05-01 23000000 1997-06-01 28360000 1997-07-01 14980000 1997-08-01 23020000 1997-09-01 28640000 1997-10-01 29820000 1997-11-01 29230000 1997-12-01 25220000 1998-01-01 21590000 1998-02-01 28110000 1998-03-01 28790000 1998-04-01 26260000 1998-05-01 25550000 1998-06-01 27470000 1998-07-01 15890000 1998-08-01 22590000 1998-09-01 28930000 1998-10-01 29570000 1998-11-01 29000000 1998-12-01 21670000 1999-01-01 26500000 1999-02-01 28130000 1999-03-01 26340000 1999-04-01 27410000 1999-05-01 25690000 1999-06-01 26640000 1999-07-01 14100000 1999-08-01 24320000 1999-09-01 28050000 1999-10-01 28840000 1999-11-01 28560000 1999-12-01 23700000 2000-01-01 25150000 2000-02-01 27820000 2000-03-01 27470000 2000-04-01 25680000 2000-05-01 27760000 2000-06-01 24360000 2000-07-01 14140000 2000-08-01 23000000 2000-09-01 28080000 2000-10-01 29240000 2000-11-01 28590000 2000-12-01 24170000 2001-01-01 26080000 2001-02-01 28410000 2001-03-01 26900000 2001-04-01 24860000 2001-05-01 24620000 2001-06-01 25140000 2001-07-01 13200000 2001-08-01 22180000 2001-09-01 26390000 2001-10-01 27320000 2001-11-01 28400000 2001-12-01 21740000 2002-01-01 22130000 2002-02-01 26990000 2002-03-01 24880000 2002-04-01 25120000 2002-05-01 22100000 2002-06-01 24810000 2002-07-01 12630000 2002-08-01 20780000 2002-09-01 25600000 2002-10-01 25700000 2002-11-01 26430000 2002-12-01 21970000 2003-01-01 19380000 2003-02-01 25350000 2003-03-01 25720000 2003-04-01 22740000 2003-05-01 23700000 2003-06-01 23100000 2003-07-01 12250000 2003-08-01 19000000 2003-09-01 25150000 2003-10-01 25530000 2003-11-01 24670000 2003-12-01 21620000 2004-01-01 17900000 2004-02-01 24770000 2004-03-01 24910000 2004-04-01 22780000 2004-05-01 22890000 2004-06-01 23410000 2004-07-01 13820000 2004-08-01 17650000 2004-09-01 25070000 2004-10-01 25080000 2004-11-01 25140000 2004-12-01 21120000 2005-01-01 21950000 2005-02-01 24050000 2005-03-01 22940000 2005-04-01 24520000 2005-05-01 22400000 2005-06-01 23190000 2005-07-01 12200000 2005-08-01 17730000 2005-09-01 24210000 2005-10-01 23840000 2005-11-01 24420000 2005-12-01 21150000 2006-01-01 21230000 2006-02-01 22830000 2006-03-01 24460000 2006-04-01 21460000 2006-05-01 21460000 2006-06-01 22390000 2006-07-01 13080000 2006-08-01 18640000 2006-09-01 24260000 2006-10-01 24910000 2006-11-01 23970000 2006-12-01 20680000 2007-01-01 22870000 2007-02-01 23240000 2007-03-01 23900000 2007-04-01 22170000 2007-05-01 21460000 2007-06-01 22600000 2007-07-01 12800000 2007-08-01 18450000 2007-09-01 24010000 2007-10-01 24720000 2007-11-01 24300000 2007-12-01 20300000 2008-01-01 20790000 2008-02-01 24140000 2008-03-01 21770000 2008-04-01 24920000 2008-05-01 22280000 2008-06-01 22480000 2008-07-01 13790000 2008-08-01 17160000 2008-09-01 23010000 2008-10-01 25170000