devon energy corporation and subsidiaries notes to consolidated financial statements 2013 ( continued ) debt maturities as of december 31 , 2015 , excluding premiums and discounts , are as follows ( millions ) : .

2016
$976
2017
—
2018
875
2019
1,100
2020
414
Thereafter
9,763
Total
$13,128

credit lines devon has a $ 3.0 billion senior credit facility .
the maturity date for $ 30 million of the senior credit facility is october 24 , 2017 .
the maturity date for $ 164 million of the senior credit facility is october 24 , 2018 .
the maturity date for the remaining $ 2.8 billion is october 24 , 2019 .
amounts borrowed under the senior credit facility may , at the election of devon , bear interest at various fixed rate options for periods of up to twelve months .
such rates are generally less than the prime rate .
however , devon may elect to borrow at the prime rate .
the senior credit facility currently provides for an annual facility fee of $ 3.8 million that is payable quarterly in arrears .
as of december 31 , 2015 , there were no borrowings under the senior credit facility .
the senior credit facility contains only one material financial covenant .
this covenant requires devon 2019s ratio of total funded debt to total capitalization , as defined in the credit agreement , to be no greater than 65% ( 65 % ) .
the credit agreement contains definitions of total funded debt and total capitalization that include adjustments to the respective amounts reported in the accompanying consolidated financial statements .
also , total capitalization is adjusted to add back noncash financial write-downs such as full cost ceiling impairments or goodwill impairments .
as of december 31 , 2015 , devon was in compliance with this covenant with a debt-to- capitalization ratio of 23.7% ( 23.7 % ) .
commercial paper devon 2019s senior credit facility supports its $ 3.0 billion of short-term credit under its commercial paper program .
commercial paper debt generally has a maturity of between 1 and 90 days , although it can have a maturity of up to 365 days , and bears interest at rates agreed to at the time of the borrowing .
the interest rate is generally based on a standard index such as the federal funds rate , libor or the money market rate as found in the commercial paper market .
as of december 31 , 2015 , devon 2019s outstanding commercial paper borrowings had a weighted-average borrowing rate of 0.63% ( 0.63 % ) .
issuance of senior notes in june 2015 , devon issued $ 750 million of 5.0% ( 5.0 % ) senior notes due 2045 that are unsecured and unsubordinated obligations .
devon used the net proceeds to repay the floating rate senior notes that matured on december 15 , 2015 , as well as outstanding commercial paper balances .
in december 2015 , in conjunction with the announcement of the powder river basin and stack acquisitions , devon issued $ 850 million of 5.85% ( 5.85 % ) senior notes due 2025 that are unsecured and unsubordinated obligations .
devon used the net proceeds to fund the cash portion of these acquisitions. .

Question: Analyse this data from a financial earnings document. in millions , what was the mathematical range of debt maturities for 2018-2020?
Choices:
-413.9
0.6
686.0
2.7
-686
Correct choice index: 2