pre_text: A summary of our outstanding debt as of December 31, 2018, is as follows (amounts in millions): Refer to Note 13 of the notes to the consolidated financial statements included in Item 8 of this Annual Report on Form 10-K for further disclosures regarding our debt obligations.
table: December 31, 2018
table: Gross Carrying Amount Unamortized Discount and Deferred Financing Costs Net Carrying Amount
table: 2021 Notes 650 (3) 647
table: 2022 Notes 400 (3) 397
table: 2026 Notes 850 (8) 842
table: 2027 Notes 400 (5) 395
table: 2047 Notes 400 (10) 390
table: Total debt $2,700 $(29) $2,671
question: Analyse this data from a financial earnings document. What was the change in gross carrying amount between the 2022 and 2026 notes?