Rates tend to fluctuate by specific region and products, particularly areas recently impacted by large catastrophic events. Although there were flooding and wind storm events and earthquakes in parts of the world, the overall 2013, 2014 and 2015 catastrophe losses for the industry were considerably lower than average. During 2016, there was an increase in catastrophes: the Fort McMurray Canadian wildfire, Hurricane Matthew which affected a large area of the Caribbean and southeastern United States, storms and an earthquake in Ecuador. There are industry predictions that the catastrophe losses for 2016 may exceed the inflation-adjusted ten year average catastrophe amounts. While the future impact on market conditions from these catastrophes cannot be determined at this time, it is unlikely to have a significant impact on the overall markets, but may impact loss affected areas.
Commencing in 2015, we initiated a strategic build out of our insurance platform through the investment in key leadership hires which in turn has brought significant underwriting talent and stronger direction in achieving our insurance program strategic goals of increased premium volume and improved underwriting results. Recent growth is coming from highly diversified areas including newly launched lines of business, as well as, product and geographic expansion in existing lines of business. We are building a world-class insurance platform capable of offering products across lines and geographies, complementing our leading global reinsurance franchise.
Premiums. Gross written premiums increased by 1.4% to $5,063.7 million in 2016, compared to $4,995.6 million in 2015, reflecting, a $195.0 million, or 13.2%, increase in our insurance business, partially offset by a $127.0 million, or 3.6%, decrease in our reinsurance business. The rise in insurance premiums was primarily due to increases in most lines of business, as we have focused on expanding the insurance operations. The decline in reinsurance premiums was mainly due to a decrease in treaty property business, a decline in international premiums related to quota share agreements and a negative impact of $42.9 million from the year over year movement in foreign exchange rates. Net written premiums decreased by 2.2% to $2,048.1 million in 2016, compared to $2,093.3 million in 2015. The decline in net written
Other Income (Expense). We recorded other expense of $10.5 million in 2016, other income of $29.3 million in 2015 and other expense of $22.3 million in 2014. The changes were primarily the result of fluctuations in foreign currency exchange rates for the corresponding periods.
Incurred Losses and Loss Adjustment Expenses. The following table presents our incurred losses and loss adjustment expenses ("LAE") for the periods indicated.
Incurred losses and LAE increased by 2.3% to $1,350.3 million in 2016 compared to $1,319.6 million in 2015, primarily due to an increase of $111.7 million in current year catastrophe losses, partially offset by higher favorable prior years attritional development of $50.8 million and higher favorable prior years catastrophe development of $34.4 million in 2016 compared to 2015. The $46.1 million of favorable prior years attritional loss development in 2016 was comprised of $142.6 million of favorable development in the reinsurance segments, partially offset by $96.5 million in the insurance segment. The favorable development in the reinsurance segments is primarily due to property and short-tail business in the U.S., as well as, property business in Canada, Latin America, the Middle East and Africa, partially offset by $45.7 million of adverse development on A&E. Part of the favorable development in the reinsurance segments related to the 2015 loss from the explosion at the Chinese port of Tianjin. In 2015, this loss was originally estimated to be $21.6 million. At December 31, 2016, this loss was projected to be $6.3 million resulting in $15.3 million of favorable development. The adverse development in the insurance segment is primarily attributable to run-off construction liability and umbrella program business. The $45.6 million of prior years' catastrophe development mainly related to the 2015 Chile earthquake, the 2011 Japan earthquake and the 2015 U.S. storms. The current year catastrophe losses of $154.8 million in 2016 were related to Hurricane Matthew ($62.3 million), the Fort McMurray Canada wildfire ($26.6 million), the 2016 U.S. Storms ($25.7 million), the Ecuador earthquake ($11.6 million), the 2016 Taiwan earthquake ($7.5 million), the Tennessee wildfire ($7.3 million), the New Zealand earthquake ($6.9 million) and Hurricane Hermine ($6.8 million). Current year catastrophe losses were $43.1 million in 2015 and related to the 2015 Chilean earthquake ($17.4 million), Northern Chile storms ($9.6 million), the 2015 US Storms ($8.1 million) and the New South Wales storms ($8.0 million).
primarily to casualty and property treaty business and was net of $30.9 million of development in asbestos reserves. Current year catastrophe losses were $43.1 million in 2015 and related to the 2015 Chilean earthquake ($17.4 million), Northern Chile storms ($9.6 million), the 2015 US Storms ($8.1 million) and the New South Wales storms ($8.0 million). The $41.8 million of current year catastrophe losses for the year ended December 31, 2014 represented 2.0 points and related to the Japan snowstorm ($13.9 million), the 2014 Chilean earthquake ($10.4 million), Hurricane Odile ($10.1 million) and the Brisbane hailstorm ($7.5 million). The $11.2 million of favorable development in prior years catastrophes related primarily to Typhoon Fitow.
Commission, Brokerage, Taxes and Fees. Commission, brokerage, taxes and fees decreased by 8.0% to $290.0 million in 2016 compared to $315.1 million in 2015. This change was primarily due to the impact of the decrease in premiums earned, the impact of affiliated quota share agreements and the changes in the mix of business.
Commission, brokerage, taxes and fees decreased by 7.2% to $315.1 million in 2015 compared to $339.4 million in 2014. This change was primarily due to the impact of changes in the mix of business and the impact of affiliated quota share agreements.
Corporate Expenses. Corporate expenses, which are general operating expenses that are not allocated to segments, were $8.3 million, $7.2 million and $7.3 million for the years ended December 31, 2016, 2015 and 2014, respectively. The increase in corporate expenses for 2016 compared to 2015 was due to higher compensation costs.
Interest, Fees and Bond Issue Cost Amortization Expense. Interest, fees and other bond amortization expense was flat at $35.4 million in 2016 and 2015.
Our combined ratio increased by 3.7 points to 90.0% in 2016 compared to 86.3% in 2015. The loss ratio component increased 2.9 points in 2016 over the same period last year. The change was mainly due to the increase in current year catastrophes in 2016 compared to 2015, partially offset by more favorable development on prior years attritional losses and prior years catastrophe losses year over year. The commission and brokerage ratio components decreased 0.9 points to 13.8% in 2016 from 14.7% in 2015 due to the impact of affiliated quota share agreements and changes in the mix of business. The other underwriting expense ratio components increased 1.7 points in 2016 over the same period last year due to the increased focus on the expansion of the insurance business.
Stockholders' equity increased by $334.3 million to $5,265.6 million at December 31, 2016 from $4,931.2 million at December 31, 2015, principally as a result of $295.8 million of net income, $25.4 million of net unrealized appreciation on investments, net of tax, $12.8 million of share-based compensation transactions and $2.8 million of net foreign currency translation adjustments, partially offset by $2.4 million of net benefit plan obligation adjustments.
Net realized capital losses were $28.9 million in 2016, and net realized capital gains were $50.3 million and $206.7 million in 2015 and 2014, respectively. In 2016, we recorded a realized capital loss of $28.0 million from the sale of our Heartland subsidiary, $25.7 million of other-than-temporary impairments and $21.1 million of net realized capital losses from sales of fixed maturity and equity securities, partially offset by $45.9 million of net realized capital gains due to fair value re-measurements on fixed maturity securities,
Gross written premiums decreased by 0.3% to $2,147.9 million in 2015 from $2,154.5 million in 2014, primarily due to a decline in treaty casualty business resulting from the cancellation of some contracts. Net written premiums decreased by 8.0% to $899.9 million in 2015 compared to $977.9 million in 2014. The difference between the change in gross written premiums compared to the change in net written premiums is primarily due to a varying utilization of reinsurance primarily related to affiliated quota share contracts. Premiums earned decreased 3.7% to $951.5 million in 2015 compared to $988.3 million in 2014. The change in premiums earned relative to net written premiums is primarily the result of timing; premiums are earned ratably over the coverage period whereas written premiums are recorded at the initiation of the coverage period.
Incurred losses increased by 34.1% to $554.1 million in 2016 compared to $413.3 million in 2015, primarily due to an increase of $82.0 million in current year attritional losses, resulting mainly from the impact of the increase in premiums earned and impact of the new crop reinsurance contract effective upon the sale of Heartland, and an increase of $58.6 million in current year catastrophe losses. The $49.0 million of favorable prior years attritional loss development in 2016 is primarily due to U.S. property and marine business, partially offset by $47.1 million of adverse development on A&E reserves. There was also an increase in favorable development of $14.6 million on prior years catastrophe losses in 2016 compared to 2015. The $19.5 million of favorable development on prior years catastrophes in 2016 mainly related to the 2011 Japan earthquake ($10.3 million), the 2015 U.S. storms ($5.8 million) and the 2013 U.S. storms ($4.8 million). The current year catastrophe losses of $67.0 million in 2016 related to Hurricane Matthew ($43.1 million), the 2016 U.S. Storms ($10.2 million), the Tennessee wildfire ($7.3 million) and Hurricane Hermine ($6.7 million). The $8.4 million of current year catastrophe losses in 2015 were mainly due to the 2015 US Storms ($8.2 million).
Segment Expenses. Commission and brokerage decreased by 4.8% to $189.5 million in 2016 compared to $199.0 million in 2015. The decrease is mainly due to the impact of the new crop reinsurance contract effective upon the sale of Heartland, the impact of affiliated quota share contracts and changes in the mix of business. Segment other underwriting expenses increased to $54.1 million in 2016 from $50.1 million in 2015. The increase was primarily due to the impact of changes in the mix of business and higher compensation costs.
Gross written premiums decreased by 15.7% to $1,374.0 million in 2015 compared to $1,630.4 million in 2014, primarily due to the decline in Latin American and Asian business, reductions in premiums related to quota share agreements and the negative impact of approximately $86.8 million from the movement of foreign exchange rates. Net written premiums decreased by 8.1% to $562.7 million in 2015 compared to $612.2 million in 2014. The difference between the change in gross written premiums compared to the change in net written premiums is primarily due to varying utilization of reinsurance related to the quota share contracts. Premiums earned decreased 3.3% to $581.2 million in 2015 compared to $601.0 million in 2014. The change in premiums earned relative to net written premiums is primarily the result of timing; premiums are earned ratably over the coverage period whereas written premiums are recorded at the initiation of the coverage period.
Segment Expenses. Commission and brokerage decreased 8.0% to $111.5 million in 2016 compared to $121.2 million in 2015. The year over year decrease was mainly due to the impact of the decrease in premiums earned. Segment other underwriting expenses remained the same at $34.3 million in 2016 and 2015.
Incurred losses and LAE increased by 15.1% to $588.6 million in 2016 compared to $511.5 million in 2015, mainly due to an increase of $38.8 million in current year attritional losses, an increase of $22.2 million in current year catastrophe losses, an increase of $16.7 million in prior years' attritional losses mainly related to run-off construction liability and umbrella business and the impact of increase in premiums earned. The increase in current year attritional losses primarily related to the impact of several non-catastrophic weather events, a slight deterioration in non-standard automobile business and growth in accident and health business, which tends to have a higher loss ratio, The $22.2 million of current year catastrophe losses in 2016 were due to the U.S. storms ($15.0 million), Hurricane Matthew ($5.5 million) and the Fort McMurray Canada wildfire ($1.7 million). There were no current year catastrophe losses for the year ended December 31, 2015.
Segment Expenses. Commission and brokerage decreased to ($11.0) million in 2016 compared to ($5.1) million in 2015. The decrease was mainly due to the impact of changes in the mix of business and the impacts from affiliated quota share agreements. Segment other underwriting expenses increased to $156.6 million in 2016 compared to $130.4 million in 2015. The increase was primarily due to increased expenses due to the build out of our insurance platform.