Comparing our results in 2017, we've taken our attritional ratio down by nine points to 55.1 this year and brought our current year ex-cat combined ratio by 10 points to 88.7, the best since 2007.
All the while, we reduced our PML by over 50% across the curve.
In 2021, industry cat losses are up about 40%, and but our cat loss ratio stayed flat at nine and a half.
This is still higher than we target, even in a $100 billion-plus cat year, and we're actively continuing our disciplined actions to reduce our cat exposure and deliver more consistent earnings.
Importantly, we continue to build a very successful specialty insurance franchise, which produced $4.9 billion of gross premium in 2021, making up 63% of our writings, up from 50% in 2017.
We expect that number to approach 70% this year as we capitalize on our already well-established presence in some of the most attractive P&C markets today.
Our insurance business is producing excellent results, growing production by 20%, generating record new business and total premiums, while at the same time, strengthening the overall portfolio.
Our insurance segment delivered a combined ratio of 91.6 this year, the best since 2010 and a parent year ex-cat combined ratio of 85.9, the lowest since 2006.
Our reinsurance business also delivered improved performance and it's an encouraging sign of progress that in a very high cat year for the industry, it produced a combined ratio below 100.
In addition, the current year ex-cat combined ratio of 86.3 was the best since 2012.
Indeed, during the recent January 1 renewals, where we write more than 50% of our reinsurance business, we advanced our corporate objectives to reduce volatility, allocate capital rigorously, and produce the most optimized portfolio for the current market.
As such, we took decisive action and reduced our reinsurance property and property cat premiums by 45%.
During the quarter, we generated net income available to common shareholders of $197 million and an annualized ROE of 16.4%.
Operating income was 182 million, and annualized operating ROE was 15.1%.
The combined ratio for the quarter was 93.1%, with core underwriting results continuing to show improvement.
The company produced a consolidated current accident year combined ratio ex-cat and weather of 89.5 points, or 2.3 points better than the prior year quarter.
The consolidated current accident year loss ratio ex-cat and weather was 54.3%, a decrease of more than three points over the prior year quarter.
The quarter's pre-tax cat and weather-related losses net of reinsurance were $54 million or 4.3 points.
This compares to 198 million or 18.4 points in 2020.
2020 did include 125 million or 11.6 points attributable to the COVID-19 pandemic.
There was no change in the total net loss estimate of 360 million established in 2020 for the COVID pandemic.
We reported net favorable prior year development of $9 million in the quarter, and this compared to 7 million in the fourth quarter of 2020.
The consolidated acquisition cost ratio was 20.4%, a decrease of 0.9 point over the prior year quarter, and that was attributable to both segments.
The consolidated G&A expense ratio was 14.8%, an increase of 1.7 points compared to the fourth quarter of '20.
The fourth quarter '21 ratio was 13.5%, and this would compare to a normalized 4Q 2020 of 13.8%.
We continue to focus on expense efficiency and expect to achieve a mid-13 G&A ratio going forward.
And lastly, on a consolidated basis, fee income from strategic capital partners was 27 million for the quarter, compared to 13 million in the prior year, largely associated with an increase in our investment manager of performance fees.
Gross premiums written increased by 19% to 1.3 billion, making it our highest fourth quarter ever.
I would also note that the year-to-date gross premiums written of 4.9 billion, was also a record for the insurance segment.
The current accident year loss ratio ex-cat weather decreased by 5.3 points, resulting from not only the impact of favorable rate over trend but also driven by improved loss experience in several lines of business.
Pretax catastrophe and weather-related losses net of reinsurance were 23 million.
I would note that the fourth quarter is the smallest quarter for gross premiums written for reinsurance representing less than 10% of their annual gross premiums.
The current accident year loss ratio ex-cat weather increased by 0.2 point, resulting from the change in business mix as we increased writings in accident and health and liability along with a decrease in premiums earned in catastrophe and credit surety businesses.
Pretax catastrophe and weather-related losses net of reinsurance were 32 million.
The acquisition cost ratio decreased by 0.4 points compared to the prior year quarter.
Net investment income was 128 million for the quarter, and this compared to net investment income of 110 million for the fourth quarter of 2020.
With respect to yields, at the end of the year, the fixed income portfolio had a book yield of 1.9% and a duration of three years, and our new money yield was 1.7%.
Diluted book value per share increased to $55.78.
The average rate increase in our insurance book was more than 14% for the fourth quarter.
For the full year, rates also averaged up 14%, which was nearly identical to the increases that we saw in 2020.
By class of business, professional lines once again saw the strongest pricing actions with average rate increases of close to 24% for the quarter and nearly 22% for the year.
For the quarter, Cyber increased nearly 80% and averaged 50% for the year.
Excluding cyber, other professional lines are averaging 13% for the quarter and 14% for the year.
Breaking it out further, London is averaging more than 18% for the quarter and the year, Canada is averaging more than 30% for the quarter and 24% for the year, while in the U.S., rates are averaging about 9% for the quarter and about 11% for the year.
Property rates increases were close to 10% for both the quarter and the year.
This included renewable energy, where we're a global leader at 13% for the quarter and the year.
While in marine and political risks, those increased 11% for the quarter, with an annual average just shy of 8%.
During the quarter, 96% of our insurance portfolio renewed flat to up and about half of the increases were double digit.
We estimate that for the full year 2021, we averaged reinsurance rate increases of about 11%.
So I'll focus my comments on 1/1.
There's been a lot of talk already in the industry about 1/1 and there's no doubt that pricing is making further progress.
At AXIS, during the January 1 renewals, we saw average rate increases of about 9%.
Our international book renewed at average increases of more than 10%, while our North American book generated increases of 9%.
In those loss impacted treaties, you would have seen increases in the 25% to 50% range.
This was evidenced by a 70% reduction in gross premiums for aggregate treaties and a 75% reduction in gross premiums on low-attaching treaties among our various actions, leading to a 45% reduction in property and property cat reinsurance premiums at the 1/1 renewals as compared to the prior year.
Given the changes expected to our portfolio to reduce both frequency and severity, our average rate increase on profit was 7%.
So with reduction to the property and catastrophe exposure, these two lines represented about 17% of our 1/1 renewal premiums, down from 27% in the 1/1 renewal portfolio last year.

Summary:
During the quarter, we generated net income available to common shareholders of $197 million and an annualized ROE of 16.4%.