note 6 : inventories we use the last-in , first-out ( lifo ) method for the majority of our inventories located in the continental u.s . other inventories are valued by the first-in , first-out ( fifo ) method . fifo cost approximates current replacement cost . inventories measured using lifo must be valued at the lower of cost or market . inventories measured using fifo must be valued at the lower of cost or net realizable value . inventories at december 31 consisted of the following: .
what was the percentage change in raw materials and supplies between 2017 and 2018?
inventories valued under the lifo method comprised $ 1.57 billion and $ 1.56 billion of total inventories at december 31 , 2018 and 2017 , respectively . note 7 : financial instruments financial instruments that potentially subject us to credit risk consist principally of trade receivables and interest- bearing investments . wholesale distributors of life-science products account for a substantial portion of our trade receivables ; collateral is generally not required . we seek to mitigate the risk associated with this concentration through our ongoing credit-review procedures and insurance . a large portion of our cash is held by a few major financial institutions . we monitor our exposures with these institutions and do not expect any of these institutions to fail to meet their obligations . major financial institutions represent the largest component of our investments in corporate debt securities . in accordance with documented corporate risk-management policies , we monitor the amount of credit exposure to any one financial institution or corporate issuer . we are exposed to credit-related losses in the event of nonperformance by counterparties to risk-management instruments but do not expect any counterparties to fail to meet their obligations given their high credit ratings . we consider all highly liquid investments with a maturity of three months or less from the date of purchase to be cash equivalents . the cost of these investments approximates fair value . our equity investments are accounted for using three different methods depending on the type of equity investment : 2022 investments in companies over which we have significant influence but not a controlling interest are accounted for using the equity method , with our share of earnings or losses reported in other-net , ( income ) expense . 2022 for equity investments that do not have readily determinable fair values , we measure these investments at cost , less any impairment , plus or minus changes resulting from observable price changes in orderly transactions for the identical or similar investment of the same issuer . any change in recorded value is recorded in other-net , ( income ) expense . 2022 our public equity investments are measured and carried at fair value . any change in fair value is recognized in other-net , ( income ) expense . we review equity investments other than public equity investments for indications of impairment on a regular basis . our derivative activities are initiated within the guidelines of documented corporate risk-management policies and are intended to offset losses and gains on the assets , liabilities , and transactions being hedged . management reviews the correlation and effectiveness of our derivatives on a quarterly basis. .