and when we believe a return of capital would be beneficial to our shareholders or joint venture and managed fund investors. In using joint ventures and managed funds, we aim to leverage our access to business and our underwriting capabilities on an efficient capital base, develop fee income, generate profit commissions, diversify our portfolio, and provide attractive risk-adjusted returns to our capital providers. We also routinely evaluate and review potential joint venture and managed fund opportunities and strategic investments. We believe we are well positioned to fulfill our objectives by virtue of the experience and skill of our management team, our integrated and flexible underwriting and operating platform, our significant financial strength, our strong relationships with brokers and customers, our commitment to superior service and our proprietary modeling technology. In particular, we believe our strategy, high performance culture, and commitment to our customers and joint venture and managed fund partners help us to differentiate ourselves by offering specialized services and products at times and in markets where capacity and alternatives may be limited. (G"N)( Our reportable segments are defined as follows: (1) Property, which is comprised of catastrophe and other property (re)insurance written on behalf of our operating subsidiaries, joint ventures and managed funds; and (2) Casualty and Specialty, which is comprised of casualty and specialty (re)insurance written on behalf of our operating subsidiaries, joint ventures and managed funds. In addition to our two reportable segments, we have an Other category, which primarily includes our strategic investments, investments unit, corporate expenses, capital servicing costs, noncontrolling interests and certain expenses related to acquisitions and dispositions. The following table shows gross premiums written allocated between our segments. Operating results relating to our segments are included in “Part II, Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.” Year ended December 31, 2021 2020 2019 (in thousands, except percentages) Gross %remiFms ,ritten %ercenta8e o7 Gross %remiFms ,ritten Gross %remiFms ,ritten %ercenta8e o7 Gross %remiFms ,ritten Gross %remiFms ,ritten %ercenta8e o7 Gross %remiFms ,ritten Property $ 3,958,724 50.5 % $ 2,999,142 51.7 % $ 2,430,985 50.6 % Casualty and Specialty 3,875,074 49.5 % 2,807,023 48.3 % 2,376,765 49.4 % Total gross premiums written $ 7,833,798 100.0 % $ 5,806,165 100.0 % $ 4,807,750 100.0 % We write proportional business as well as excess of loss business. In addition, Syndicate 1458 and RenaissanceRe Specialty U.S. write insurance business through delegated authority arrangements, which are included in our Property and Casualty and Specialty segments, as appropriate. Our relative mix of business between proportional business and excess of loss business has fluctuated in the past and will likely vary in the future. Proportional and delegated authority business typically have relatively higher premiums per unit of expected underwriting income, together with a higher acquisition expense ratio and combined ratio, than traditional excess of loss reinsurance, as these coverages tend to be exposed to relatively more attritional, and frequent, losses while being subject to less expected severity. 5