credit commitments and lines of credit the table below summarizes citigroup 2019s credit commitments : in millions of dollars u.s . outside of u.s . december 31 , december 31 .

Table:
in millions of dollars | u.s . | outside ofu.s . | december 312018 | december 31 2017
commercial and similar letters of credit | $ 823 | $ 4638 | $ 5461 | $ 5000
one- to four-family residential mortgages | 1056 | 1615 | 2671 | 2674
revolving open-end loans secured by one- to four-family residential properties | 10019 | 1355 | 11374 | 12323
commercial real estate construction and land development | 9565 | 1728 | 11293 | 11151
credit card lines | 605857 | 90150 | 696007 | 678300
commercial and other consumer loan commitments | 185849 | 102918 | 288767 | 272655
other commitments and contingencies | 2560 | 761 | 3321 | 3071
total | $ 815729 | $ 203165 | $ 1018894 | $ 985174
the majority of unused commitments are contingent upon customers maintaining specific credit standards .
commercial commitments generally have floating interest rates and fixed expiration dates and may require payment of fees .
such fees ( net of certain direct costs ) are deferred and , upon exercise of the commitment , amortized over the life of the loan or , if exercise is deemed remote , amortized over the commitment period .
commercial and similar letters of credit a commercial letter of credit is an instrument by which citigroup substitutes its credit for that of a customer to enable the customer to finance the purchase of goods or to incur other commitments .
citigroup issues a letter on behalf of its client to a supplier and agrees to pay the supplier upon presentation of documentary evidence that the supplier has performed in accordance with the terms of the letter of credit .
when a letter of credit is drawn , the customer is then required to reimburse citigroup .
one- to four-family residential mortgages a one- to four-family residential mortgage commitment is a written confirmation from citigroup to a seller of a property that the bank will advance the specified sums enabling the buyer to complete the purchase .
revolving open-end loans secured by one- to four-family residential properties revolving open-end loans secured by one- to four-family residential properties are essentially home equity lines of credit .
a home equity line of credit is a loan secured by a primary residence or second home to the extent of the excess of fair market value over the debt outstanding for the first mortgage .
commercial real estate , construction and land development commercial real estate , construction and land development include unused portions of commitments to extend credit for the purpose of financing commercial and multifamily residential properties as well as land development projects .
both secured-by-real-estate and unsecured commitments are included in this line , as well as undistributed loan proceeds , where there is an obligation to advance for construction progress payments .
however , this line only includes those extensions of credit that , once funded , will be classified as total loans , net on the consolidated balance sheet .
credit card lines citigroup provides credit to customers by issuing credit cards .
the credit card lines are cancelable by providing notice to the cardholder or without such notice as permitted by local law .
commercial and other consumer loan commitments commercial and other consumer loan commitments include overdraft and liquidity facilities as well as commercial commitments to make or purchase loans , purchase third-party receivables , provide note issuance or revolving underwriting facilities and invest in the form of equity .
other commitments and contingencies other commitments and contingencies include committed or unsettled regular-way reverse repurchase agreements and all other transactions related to commitments and contingencies not reported on the lines above .
unsettled reverse repurchase and securities lending agreements and unsettled repurchase and securities borrowing agreements in addition , in the normal course of business , citigroup enters into reverse repurchase and securities borrowing agreements , as well as repurchase and securities lending agreements , which settle at a future date .
at december 31 , 2018 , and 2017 , citigroup had $ 36.1 billion and $ 35.0 billion unsettled reverse repurchase and securities borrowing agreements , respectively , and $ 30.7 billion and $ 19.1 billion unsettled repurchase and securities lending agreements , respectively .
for a further discussion of securities purchased under agreements to resell and securities borrowed , and securities sold under agreements to repurchase and securities loaned , including the company 2019s policy for offsetting repurchase and reverse repurchase agreements , see note 11 to the consolidated financial statements. .

Question: what percentage of total credit commitments as of december 31 , 2018 are credit card lines?
Answer: 68%
Calculation: divide(696007, 1018894)