references in this section are to all of our U.S. and non-U.S. plans. None of our common stock is directly held by these plans. Our U.S. defined benefit plan assets consist of a balanced portfolio of equity and fixed income securities. Our non-U.S. defined benefit plan assets include a significant concentration of United Kingdom ("U.K.") fixed income securities, as discussed in Note 14 to our consolidated financial statements included in Item 8 of this Annual Report. We monitor investment allocations and manage plan assets to maintain an acceptable level of risk. At December 31, 2020, the estimated fair market value of U.S. and non-U.S. plan assets for our defined benefit pension plans increased to $765.0 million from $745.1 million at December 31, 2019. Assets were allocated as follows: U.S. Plan Asset category 2020 2019 Cash and Cash Equivalents 1  % 1  % Global Equity 30  % 28  % Global Real Assets 13  % 12  % Equity securities 43  % 40  % Diversified Credit 14  % 12  % Liability-Driven Investment 42  % 47  % Fixed income 56  % 59  % Non-U.S. Plans Asset category 2020 2019 Cash and Cash Equivalents 1  % 2  % North American Companies 1  % 1  % Global Equity 1  % 1  % Equity securities 2  % 2  % U.K. Government Gilt Index 39  % 43  % Liability-Driven Investment 12  % 7  % Fixed income 51  % 50  % Multi-asset 20  % 19  % Buy-in Contract 20  % 21  % Other 6  % 6  % Other types 46  % 46  % The projected benefit obligation ("Benefit Obligation") for our defined benefit pension plans wa s $957.4 million  and $897.1 million as of December 31, 2020 and 2019, respectively. Benefits under our defined benefit pension plans are based primarily on participants’ compensation and years of credited service. We sponsor defined benefit postretirement medical plans covering certain current retirees and a limited number of future retirees in the U.S. These plans provide for medical and dental benefits and are administered through insurance companies. We fund the plans as benefits are paid, such that the plans hold no assets in any period presented. Accordingly, we have no investment strategy or targeted allocations for plan assets. The benefits under the plans are not available to new employees or most existing employees. The Benefit Obligation for our defined benefit postretirement medical plans was $18 .6 million  and $18.9 million as of December 31, 2020 and 2019, respectively. We account for pension benefits using the accrual method, recognizing pension expense before the payment of benefits to retirees. The accrual method of accounting for pension benefits requires actuarial assumptions concerning future events that will determine the amount and timing of the benefit payments. Accrual Accounting and Significant Assumptions 48