The net claims and claim expense ratio for prior accident years reflected net favorable development of 15.3% for the catastrophe class of business and 2.4% for the other property class of business, primarily related to weather-related large losses in the 2017 to 2019 accident years. The underwriting expense ratio decreased 1.0 percentage point , principally driven by improved operating leverage, through higher net premiums earned, including $293.3 million of net reinstatement premiums earned associated with the 2021 Weather-Related Large Losses. Our Property segment generated underwriting income of $11. 0 million in 2020, compared to $209.3 million in 2019, a decrease of $198.1 million. In 2020, our Property segment generated a net claims and claim expense ratio of 74.2%, an underwriting expense ratio of 25.2% and a combined ratio of 99.4%, compared to 59.3%, 27.8% and 87.1%, respectively, in 2019. Principally impacting the Property segment underwriting result and combined ratio in 2020 were the 2020 Weather-Related Large Loss Events, which resulted in a net negative impact on the underwriting result of $651.9 million and added 35.0 percentage points to the combined ratio, and COVID-19 losses, which resulted in a net negative impact on the underwriting result of $235.0 million and added 12.3 percentage points to the combined ratio. Partially offsetting the impact of the 2020 Weather-Related Large Loss Events and COVID-19 losses was favorable development on prior accident years of $157.3 million, primarily related to large loss events in 2019, 2018 and 2017, as well as favorable movements in other assumed losses and ceded recoveries. This favorable development reduced the Property segment combined ratio by 8.1 percentage points. In comparison, 2019 was principally impacted by the 2019 Large Loss Events, which resulted in a net negative impact on the Property segment underwriting result of $414.4 million and a corresponding increase in the Property segment combined ratio of 26.7 percentage points. Refer to “Part II, Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations—Summary of Critical Accounting Estimates—Claims and Claim Expense Reserves” and “Note 8. Reserve for Claims and Claim Expenses” in our “Notes to the Consolidated Financial Statements” for additional discussion of our reserving techniques and prior year development of net claims and claim expenses. 80