Table of Contents The following table summarizes the gross and net carried reserves for International. Net written premiums for International increased $60 million in 2017 as compared with 2016 due to higher new business, positive renewal premium change and higher retention. Excluding the effect of foreign currency exchange rates, net written premiums increased 8.1% in 2017. The increase in net earned premiums was consistent with the trend in net written premiums. Core income decreased $13 million in 2017 as compared with 2016 driven by lower favorable net prior year loss reserve development and higher net catastrophe losses partially offset by favorable period over period foreign currency exchange results. The combined ratio of 104.8% increased 5.7 points in 2017 as compared with 2016. The loss ratio increased 6.0 points, primarily due to lower favorable net prior year loss reserve development and higher net catastrophe losses partially offset by lower current accident year large losses. Net catastrophe losses were $64 million, or 7.9 points of the loss ratio, for 2017, as compared with $31 million, or 3.9 points of the loss ratio, for 2016. The loss ratio excluding catastrophes and development improved 3.0 points. The expense ratio improved 0.3 points in 2017 as compared with 2016 primarily due to the higher net earned premiums. Favorable net prior year loss reserve development of $9 million and $58 million was recorded in 2017 and 2016. Further information on net prior year loss reserve development is in Note E to the Consolidated Financial Statements included under Item 8. 38 2017 Compared with 2016 December 31 (In millions) 2018 2017 Gross case reserves $ 867 $ 744 Gross IBNR reserves 883 892 Total gross carried claim and claim adjustment expense reserves $ 1,750 $ 1,636 Net case reserves $ 749 $ 640 Net IBNR reserves 775 792 Total net carried claim and claim adjustment expense reserves $ 1,524 $ 1,432