The components of long-term debt (net of discounts and debt issuance costs), along with maturity dates for the years subsequent to May 31, 2019, are as follows (in millions):

				May 31,
				2019		2018
	Interest Rate%		Maturity
Senior unsecured debt:		8.00	2019	$	—	$	750
		2.30	2020		400		399
		3.40	2022		497		—
	2.625-2.70		2023		747		746
		4.00	2024		746		746
		3.20	2025		696		695
		3.25	2026		745		744
		3.30	2027		446		445
		3.40	2028		495		495
		4.20	2029		396		—
		4.90	2034		495		495
		3.90	2035		494		493
	3.875-4.10		2043		984		983
		5.10	2044		742		742
		4.10	2045		641		640
	4.55-4.75		2046		2,460		2,459
		4.40	2047		735		735
		4.05	2048		986		986
		4.95	2049		835		—
		4.50	2065		246		246
		7.60	2098		237		237
Euro senior unsecured debt:	floating-rate		2019		—		582
		0.50	2020		559		581
		0.70	2022		713		—
		1.00	2023		836		869
		1.625	2027		1,387		1,442
Total senior unsecured debt					17,518		16,510
Other debt					1		4
Capital lease obligations					62		71
					17,581		16,585
Less current portion					964		1,342
				$	16,617	$	15,243

Interest on our U.S. dollar fixed-rate notes is paid semi-annually. Interest on our euro fixed-rate notes is paid annually. The weighted average interest rate on long-term debt was 3.5% as of May 31, 2019. Long-term debt, including current maturities and exclusive of capital leases, had estimated fair values of $17.8 billion at May 31, 2019 and $16.6 billion at May 31, 2018. The estimated fair values were determined based on quoted market prices and the current rates offered for debt with similar terms and maturities. The fair value of our long-term debt is classified as Level 2 within the fair value hierarchy. This classification is defined as a fair value determined using market-based inputs other than quoted prices that are observable for the liability, either directly or indirectly.

We have a shelf registration statement filed with the Securities and Exchange Commission (“SEC”) that allows us to sell, in one or more future offerings, any combination of our unsecured debt securities and common stock.

During January 2019, we issued $1.2 billion of senior unsecured debt under our current shelf registration statement, comprised of €640 million of 0.7% fixed-rate notes due in May 2022 and $500 million of 3.4% fixed-rate notes due in January 2022. We used the net proceeds to pay the €500 million aggregate principal amount of floating-rate notes that matured on April 11, 2019, and for general corporate purposes.

During October 2018, we issued $1.25 billion of senior unsecured debt under our current shelf registration statement, comprised of $400 million of 4.20% fixed-rate notes due in October 2028 and $850 million of 4.95% fixed-rate notes due in October 2048. We used the net proceeds to redeem the $750 million aggregate principal amount of 8.00% notes due January 15, 2019, and for general corporate purposes.

During the fourth quarter of 2019, we replaced our $2.0 billion five-year revolving credit facility with a $2.0 billion five-year credit agreement (the “Five-Year Credit Agreement”) and a $1.5 billion 364-day credit agreement (the “364-Day Credit Agreement” and, together with the Five-Year Credit Agreement, the “New Credit Agreements”). The Five-Year Credit Agreement expires in March 2024 and includes a $250 million letter of credit sublimit. The 364-Day Credit Agreement expires in March 2020. The New Credit Agreements are available to finance our operations and other cash flow needs. The New Credit Agreements contain a financial covenant requiring us to maintain a ratio of debt to consolidated earnings (excluding noncash retirement plans MTM adjustments and noncash asset impairment charges) before interest, taxes, depreciation and amortization (“adjusted EBITDA”) of not more than 3.5 to 1.0, calculated as of the end of the applicable quarter on a rolling four-quarters basis. The ratio of our debt to adjusted EBITDA was 2.25 to 1.0 at May 31, 2019. We believe this covenant is the only significant restrictive covenant in our New Credit Agreements. Our New Credit Agreements contain other customary covenants that do not, individually or in the aggregate, materially restrict the conduct of our business. We are in compliance with the financial covenant and all other covenants in our New Credit Agreements and do not expect the covenants to affect our operations, including our liquidity or expected funding needs. If we failed to comply with the financial covenant or any other covenants in our New Credit Agreements, our access to financing could become limited. We had a total of $53 million in letters of credit outstanding at May 31, 2019, with $197 million of the letter of credit sublimit unused under our revolving credit facility.