credit commitments and lines of credit the table below summarizes citigroup 2019s credit commitments as of december 31 , 2010 and december 31 , 2009: .
what percentage of citigroup 2019s credit commitments as of december 31 , 2010 are u.s.?
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 loans on the consolidated balance sheet . credit card lines citigroup provides credit to customers by issuing credit cards . the credit card lines are unconditionally cancelable by the issuer . 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 , to purchase third-party receivables , to provide note issuance or revolving underwriting facilities and to invest in the form of equity . amounts include $ 79 billion and $ 126 billion with an original maturity of less than one year at december 31 , 2010 and december 31 , 2009 , respectively . in addition , included in this line item are highly leveraged financing commitments , which are agreements that provide funding to a borrower with higher levels of debt ( measured by the ratio of debt capital to equity capital of the borrower ) than is generally considered normal for other companies . this type of financing is commonly employed in corporate acquisitions , management buy-outs and similar transactions. .