The following is a reconciliation of net earnings of Flowserve Corporation and weighted average shares for calculating net earnings per common share: Diluted earnings per share is based upon the weighted average number of shares as determined for basic earnings per share plus shares potentially issuable in conjunction with stock options, restricted shares, restricted share units and performance share units. Research and Development Expense — Research and development costs are charged to expense when incurred. Aggregate research and development costs included in SG&A were $42.0 million, $39.6 million and $38.6 million in 2019, 2018 and 2017, respectively. Costs incurred for research and development primarily include salaries and benefits and consumable supplies, as well as rent, professional fees, utilities and the depreciation of property and equipment used in research and development activities. In February 2016, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2016-02, Leases (Topic 842) ("New Lease Standard"). The New Lease Standard increases transparency and comparability by requiring lessees to recognize right-of-use (“ROU”) assets and lease liabilities for operating leases on their consolidated balance sheets. Additionally, expanded disclosures are required to enable users of financial statements to understand the amount, timing and uncertainty of cash flows arising from leases. We adopted the New Lease Standard effective January 1, 2019, utilizing the modified retrospective approach and elected an initial application date of January 1, 2019. The adoption resulted in an increase to total assets and liabilities due to the recording of lease ROU assets and lease liabilities of approximately $225 million as of January 1, 2019. The adoption did not materially impact our consolidated results of operations or cash flows. Refer to Note 4 for further discussion of our adoption of the New Lease Standard. On July 13, 2017, the FASB issued ASU No. 2017-11, “Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815): (Part I) Accounting for Certain Financial Instruments with Down Round Features, (Part II) Replacement of the Indefinite Deferral for Mandatory Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatory Redeemable Noncontrolling Interests with a Scope Exception.” The ASU amends guidance in FASB Accounting Standards Codification ("ASC") 260, Earnings Per Share, FASB ASC 480, Distinguishing Liabilities from Equity, and FASB ASC 815, Derivatives and Hedging. The amendments in Part I of this ASU change the classification analysis of certain equity-linked financial instruments (or embedded features) with down round features. The amendments in this ASU must be applied to annual reporting periods beginning after December 15, 2018. Our adoption of Pronouncements Implemented Accounting Developments 63 Year Ended December 31, 2019 2018 2017 (Amounts in thousands, except per share data) Net earnings of Flowserve Corporation $ 253,668 $ 119,671 $ 2,652 Dividends on restricted shares not expected to vest — — — Earnings attributable to common and participating shareholders $ 253,668 $ 119,671 $ 2,652 Weighted average shares: Common stock 131,012 130,794 130,600 Participating securities 22 29 103 Denominator for basic earnings per common share 131,034 130,823 130,703 Effect of potentially dilutive securities 685 448 655 Denominator for diluted earnings per common share 131,719 131,271 131,358 Net earnings per share attributable to Flowserve Corporation common shareholders: Basic $ 1.94 $ 0.91 $ 0.02 Diluted 1.93 0.91 0.02