The following table summarizes the major components of debt as of each balance sheet date (in millions) and provides the maturities and interest rate ranges of each major category as of December 31: | | | | | | | | | 2020 | | 2019 | Commercial paper program (weighted average interest rate of 0.4% as of December 31, 2020) | | $ | 1,814 | | $ | — | Senior notes, maturing through 2050, interest rates ranging from 0.75% to 7.75% (weighted average interest rate of 3.3% as of December 31, 2020 and 3.9% as of December 31, 2019) | | | 8,465 | | | 9,965 | Canadian senior notes, C$500 million maturing September 2026, interest rate of 2.6% | | | 393 | | | 385 | Tax-exempt bonds, maturing through 2048, fixed and variable interest rates ranging from 0.1% to 4.3% (weighted average interest rate of 1.7% as of December 31, 2020 and 2.3% as of December 31, 2019) | | | 2,571 | | | 2,523 | Financing leases and other, maturing through 2085, weighted average interest rate of 4.6% (a) | | | 652 | | | 710 | Debt issuance costs, discounts and other | | | (85) | | | (85) | | | | 13,810 | | | 13,498 | Current portion of long-term debt | | | 551 | | | 218 | | | $ | 13,259 | | $ | 13,280 |
(a) | Excluding our landfill financing leases, the maturities of our financing leases and other debt obligations extend through 2059. |
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