Computation of Ratio of Earnings to Fixed Charges

		3 Months Ended			12 Months Ended		12 Months Ended (2)
		Mar. 31			Mar. 31			Dec. 31,			Dec. 31,			Dec. 31,			Dec. 31,			Dec. 31,
		2007			2007			2006			2005			2004			2003			2002
								- Thousands of Dollars -
Fixed Charges:
Interest on Long-Term Debt	$	17,989		$	74,343		$	75,039		$	76,762		$	80,968		$	80,844		$	65,620
Other Interest (1)		1,761			8,377			7,922			3,153			1,947			3,709			2,123
Interest on Capital Lease Obligations		16,152			70,191			72,586			79,098			85,912			84,080			87,801
Total Fixed Charges		35,902			152,911			155,547			159,013			168,827			168,633			155,544

Net Income		4,943			55,569			67,447			46,144			45,919			113,941			34,928

Less:
Discontinued Operations - Net of Tax		-			873			(1,796	)		(5,483	)		(5,063	)		(7,472	)		(12,919	)
Accounting Change - Net of Tax		-			-			-			(626	)		-			67,471			-
Net Income from Continuing Operations		4,943			54,696			69,243			52,253			50,982			53,942			47,847

Add (Deduct):
(Income) Losses from Equity Investees		(16	)		(231	)		(210	)		(2,113	)		(7,121	)		3,051			3,047
Income Taxes		3,871			34,105			43,936			37,623			37,186			16,531			26,432
Total Fixed Charges		35,902			152,911			155,547			159,013			168,827			168,633			155,544

Total Earnings before Taxes and Fixed Charges	$	44,700		$	241,481		$	268,516		$	246,776		$	249,874		$	242,157		$	232,870

Ratio of Earnings to Fixed Charges		1.245			1.579			1.726			1.552			1.480			1.436			1.497