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The following tables present our fair value hierarchy for our major categories of pension plan assets by asset class as of December 31, 2010 and 2009, respectively. See Note 17 for the definition of fair value and the descriptions of Level 1, 2 and 3 in the fair value hierarchy. 

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(1) As of December 31, 2010 and 2009 we have $70.8 million and $65.4 million, respectively of investments in certain mutual funds where the net asset value reported by the underlying funds approximates the fair value. These investments are redeemable with the fund at net asset value under the original terms of the partnership agreements and/or subscription agreements and operations of the underlying funds. However, it is possible that these redemption rights may be restricted or eliminated by the funds in the future in accordance with the underlying fund agreements. Due to the nature of the investments held by the funds, changes in market conditions and the economic environment may significantly impact the net asset value of the funds and, consequently, the fair value of the interests in the funds. Furthermore, changes to the liquidity provisions of the funds may significantly impact the fair value of the interest in the funds. 

There was no change in the value of plan assets using significant unobservable inputs (level 3) from December 31, 2009 to December 31, 2010. There were no changes to the other level 3 investments during 2009. 

We made the following contributions to our pension and other postretirement benefit plans during the years ended December 31, 2010 and 2009: 

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We expect our voluntary cash contributions to our U.S. qualified pension plan to be $55.0 million in 2011. 

