	As of June 30, 2020			As of December 31, 2019
Revolving credit facility	$	—		$	—
Term loan		200,000			200,000
British pound sterling term loan(A)		868,070			—
Australian term loan facility(A)		828,360			842,520
4.000% Senior Unsecured Notes due 2022(A)		561,700			560,650
2.550% Senior Unsecured Notes due 2023(A)		496,040			530,280
5.500% Senior Unsecured Notes due 2024		300,000			300,000
6.375% Senior Unsecured Notes due 2024		500,000			500,000
3.325% Senior Unsecured Notes due 2025(A)		561,700			560,650
5.250% Senior Unsecured Notes due 2026		500,000			500,000
5.000% Senior Unsecured Notes due 2027		1,400,000			1,400,000
3.692% Senior Unsecured Notes due 2028(A)		744,060			795,420
4.625% Senior Unsecured Notes due 2029		900,000			900,000
	$	7,859,930		$	7,089,520
Debt issue costs and discount, net		(64,040	)		(65,841	)
	$	7,795,890		$	7,023,679

As of June 30, 2020, principal payments due on our debt (which exclude the effects of any discounts, premiums, or debt issue costs recorded) are as follows (in thousands):

2020	$	—
2021		—
2022		761,700
2023		496,040
2024		1,628,360
Thereafter		4,973,830
Total	$	7,859,930

On January 6, 2020, we entered into a £700 million unsecured sterling-denominated term loan facility with Bank of America, N.A., as administrative agent, and a syndicate of financial institutions as the lender. The term loan facility matures on January 15, 2025. We used the proceeds under the facility to help finance our acquisition of the Circle transaction described in Note 3. The applicable margin under the term loan is adjustable based on a pricing grid from 0.85% to 1.65% dependent on our current credit rating. On March 4, 2020, we entered into an interest rate swap transaction (effective March 6, 2020) to fix the interest rate to approximately 0.70% for the duration of the loan. The current applicable margin for the pricing grid (which can vary based on our credit rating) is 1.25% for an all-in fixed rate of 1.95%.

On May 23, 2019, we entered into an AUD $1.2 billion term loan facility agreement with Bank of America, N.A., as administrative agent, and a syndicate of financial institutions as the lender. The term loan facility matures on May 23, 2024. The interest rate under the term loan is adjustable based on a pricing grid from 0.85% to 1.65%, dependent on our current senior unsecured credit rating. On June 27, 2019, we entered into an interest rate swap transaction (effective July 3, 2019) to fix the interest rate to approximately 1.20% for the duration of the loan. The current applicable margin for the pricing grid (which can vary based on our credit rating) is 1.25% for an all-in fixed rate of 2.45%.

Our debt facilities impose certain restrictions on us, including restrictions on our ability to: incur debts; create or incur liens; provide guarantees in respect of obligations of any other entity; make redemptions and repurchases of our capital stock; prepay, redeem, or repurchase debt; engage in mergers or consolidations; enter into affiliated transactions; dispose of real estate or other assets; and change our business. In addition, the credit agreements governing our revolving credit (“Credit Facility”) limit the amount of dividends we can pay as a percentage of normalized adjusted funds from operations (“NAFFO”), as defined in the agreements, on a rolling four quarter basis. At June 30, 2020, the dividend restriction was 95% of NAFFO. The indentures governing our senior unsecured notes also limit the amount of dividends we can pay based on the sum of 95% of NAFFO, proceeds of equity issuances and certain other net cash proceeds. Finally, our senior unsecured notes require us to maintain total unencumbered assets (as defined in the related indenture) of not less than 150% of our unsecured indebtedness.

In addition to these restrictions, the Credit Facility contains customary financial and operating covenants, including covenants relating to our total leverage ratio, fixed charge coverage ratio, secured leverage ratio, consolidated adjusted net worth, unsecured leverage ratio, and unsecured interest coverage ratio. This Credit Facility also contains customary events of default, including among others, nonpayment of principal or interest, material inaccuracy of representations, and failure to comply with our covenants. If an event of default occurs and is continuing under the Credit Facility, the entire outstanding balance may become immediately due and payable. At June 30, 2020, we were in compliance with all such financial and operating covenants.