DEVON ENERGY CORPORATION AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS – (Continued) Proved Undeveloped Reserves The following table presents the changes in Devon’s total proved undeveloped reserves during 2013 (in MMBoe).
## Table 0 ##
At December 31, 2013, Devon had 701 MMBoe of proved undeveloped reserves.
This represents a 17 percent decrease as compared to 2012 and represents 24 percent of total proved reserves.
Drilling and development activities increased Devon’s proved undeveloped reserves 95 MMBoe and resulted in the conversion of 147 MMBoe, or 18 percent, of the 2012 proved undeveloped reserves to proved developed reserves.
Costs incurred related to the development and conversion of Devon’s proved undeveloped reserves were $1.9 billion for 2013.
Additionally, revisions other than price decreased Devon’s proved undeveloped reserves 78 MMBoe primarily due to evaluations of certain U. S.  onshore dry-gas areas, which Devon does not expect to develop in the next five years.
The largest revisions relate to the dry-gas areas in the Cana-Woodford Shale in western Oklahoma, Carthage in east Texas and the Barnett Shale in north Texas.
A significant amount of Devon’s proved undeveloped reserves at the end of 2013 related to its Jackfish operations.
At December 31, 2013 and 2012, Devon’s Jackfish proved undeveloped reserves were 441 MMBoe and 429 MMBoe, respectively.
Development schedules for the Jackfish reserves are primarily controlled by the need to keep the processing plants at their 35,000 barrel daily facility capacity.
Processing plant capacity is controlled by factors such as total steam processing capacity, steam-oil ratios and air quality discharge permits.
As a result, these reserves are classified as proved undeveloped for more than five years.
Currently, the development schedule for these reserves extends though the year 2031.
Price Revisions 2013 – Reserves increased 94 MMBoe primarily due to higher gas prices.
Of this increase, 43 MMBoe related to the Barnett Shale and 19 MMBoe related to the Rocky Mountain area.2012 – Reserves decreased 171 MMBoe primarily due to lower gas prices.
Of this decrease, 100 MMBoe related to the Barnett Shale and 25 MMBoe related to the Rocky Mountain area.2011 – Reserves decreased 21 MMBoe due to lower gas prices and higher oil prices.
The higher oil prices increased Devon’s Canadian royalty burden, which reduced Devon’s oil reserves.
Revisions Other Than Price Total revisions other than price for 2013, 2012 and 2011 primarily related to Devon’s evaluation of certain dry gas regions, with the largest revisions being made in the Cana-Woodford Shale, Barnett Shale and Carthage area.
Financial Strength Ratings.
The following table shows the current financial strength ratings of the Company’s operating subsidiaries as reported by A. M.  Best, Standard & Poor’s and Moody’s.
These ratings are based upon factors of concern to policyholders and should not be considered an indication of the degree or lack of risk involved in a direct or indirect equity investment in an insurance or reinsurance company.
All of the below-mentioned ratings are continually monitored and revised, if necessary, by each of the rating agencies.
The ratings presented in the following table were in effect as of February 8, 2016.
The Company believes that its ratings are important as they provide the Company’s customers and its investors with an independent assessment of the Company’s financial strength using a rating scale that provides for relative comparisons.
Strong financial ratings are particularly important for reinsurance companies.
Ceding companies must rely on their reinsurers to pay covered losses well into the future.
As a result, a highly rated reinsurer is generally preferred.
## Table 1 ##
A. M.  Best states that the “A+” (“Superior”) rating is assigned to those companies which, in its opinion, have a superior ability to meet their ongoing insurance policy and contract obligations based on A. M.  Best’s comprehensive quantitative and qualitative evaluation of a company’s balance sheet strength, operating performance and business profile.
A. M.  Best affirmed these ratings on September 9, 2015.
Standard & Poor’s states that the “A+”/”A” ratings are assigned to those insurance companies which, in its opinion, have strong financial security characteristics with respect to their ability to pay under its insurance policies and contracts in accordance with their terms.
Standard & Poor’s affirmed these ratings on June 16, 2015.
Moody’s states that an “A1” rating is assigned to companies that, in their opinion, offer upper-medium grade security and are subject to low credit risk.
Moody’s affirmed these ratings on December 21, 2015.
Subsidiaries other than Everest Re and Bermuda Re may not be rated by some or any rating agencies because such ratings are not considered essential by the individual subsidiary’s customers or because of the limited nature of the subsidiary’s operations.
Debt Ratings.
The following table shows the debt ratings by A. M.  Best, Standard & Poor’s and Moody’s of the Holdings’ senior notes due June 1, 2044 and long term notes due May 1, 2067 both of which are considered investment grade.
Debt ratings are the rating agencies’ current assessment of the credit worthiness of an obligor with respect to a specific obligation.
## Table 2 ##
The following discusses the underwriting results for each of our segments for the periods indicated.
U. S.  Reinsurance.
The following table presents the underwriting results and ratios for the U. S.  Reinsurance segment for the periods indicated.
## Table 3 ##
Premiums.
Gross written premiums decreased by 3.7% to $1,963.5 million in 2015 from $2,039.6 million in 2014, primarily due to a decrease in treaty casualty business resulting from the cancellation of some contracts.
Net written premiums decreased by 6.4% to $1,855.9 million in 2015 compared to $1,983.8 million in 2014.
The difference between the change in gross written premiums compared to the change in net written premiums was due to a higher utilization of reinsurance.
Premiums earned decreased 1.7% to $1,952.7 million in 2015 compared to $1,986.8 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.
Gross written premiums increased by 12.7% to $2,039.6 million in 2014 from $1,809.7 million in 2013, primarily due to new business opportunities, particularly for contracts with catastrophe exposed risks.
Net written premiums increased by 9.8% to $1,983.8 million in 2014 compared to $1,807.1 million in 2013, which is in line with the increase in gross written premiums combined with a higher use of reinsurance for catastrophe exposures.
Premiums earned increased 18.9% to $1,986.8 million in 2014 compared to $1,671.5 million in 2013.
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.
properly allocating responsibility and/or liability for asbestos or environmental damage; (d) changes in underlying laws and judicial interpretation of those laws; (e) the potential for an asbestos or environmental claim to involve many insurance providers over many policy periods; (f) questions concerning interpretation and application of insurance and reinsurance coverage; and (g) uncertainty regarding the number and identity of insureds with potential asbestos or environmental exposure.
Due to the uncertainties discussed above, the ultimate losses attributable to A&E, and particularly asbestos, may be subject to more variability than are non-A&E reserves and such variation could have a material adverse effect on our financial condition, results of operations and/or cash flows.
See also ITEM 8, “Financial Statements and Supplementary Data” - Notes 1 and 3 of Notes to the Consolidated Financial Statements.
Reinsurance Receivables.
We have purchased reinsurance to reduce our exposure to adverse claim experience, large claims and catastrophic loss occurrences.
Our ceded reinsurance provides for recovery from reinsurers of a portion of losses and loss expenses under certain circumstances.
Such reinsurance does not relieve us of our obligation to our policyholders.
In the event our reinsurers are unable to meet their obligations under these agreements or are able to successfully challenge losses ceded by us under the contracts, we will not be able to realize the full value of the reinsurance receivable balance.
To minimize exposure from uncollectible reinsurance receivables, we have a reinsurance security committee that evaluates the financial strength of each reinsurer prior to our entering into a reinsurance arrangement.
In some cases, we may hold full or partial collateral for the receivable, including letters of credit, trust assets and cash.
Additionally, creditworthy foreign reinsurers of business written in the U. S. , as well as capital markets’ reinsurance mechanisms, are generally required to secure their obligations.
We have established reserves for uncollectible balances based on our assessment of the collectability of the outstanding balances.
As of December 31, 2015 and 2014, the reserve for uncollectible balances was $15.0 million and $21.6 million, respectively.
Actual uncollectible amounts may vary, perhaps substantially, from such reserves, impacting income (loss) in the period in which the change in reserves is made.
See also ITEM 8, “Financial Statements and Supplementary Data” - Note 13 of Notes to the Consolidated Financial Statements and “Financial Condition – Reinsurance Receivables” below.
Premiums Written and Earned.
Premiums written by us are earned ratably over the coverage periods of the related insurance and reinsurance contracts.
We establish unearned premium reserves to cover the unexpired portion of each contract.
Such reserves, for assumed reinsurance, are computed using pro rata methods based on statistical data received from ceding companies.
Premiums earned, and the related costs, which have not yet been reported to us, are estimated and accrued.
Because of the inherent lag in the reporting of written and earned premiums by our ceding companies, we use standard accepted actuarial methodologies to estimate earned but not reported premium at each financial reporting date.
These earned but not reported premiums are combined with reported earned premiums to comprise our total premiums earned for determination of our incurred losses and loss and LAE reserves.
Commission expense and incurred losses related to the change in earned but not reported premium are included in current period company and segment financial results.
See also ITEM 8, “Financial Statements and Supplementary Data” - Note 1 of Notes to the Consolidated Financial Statements.
The following table displays the estimated components of net earned but not reported premiums by segment for the periods indicated.
## Table 4 ##

<table><tr><td></td><td>U.S.</td><td>Canada</td><td>Total</td></tr><tr><td>Proved undeveloped reserves as of December 31, 2012</td><td>407</td><td>433</td><td>840</td></tr><tr><td>Extensions and discoveries</td><td>57</td><td>38</td><td>95</td></tr><tr><td>Revisions due to prices</td><td>1</td><td>-10</td><td>-9</td></tr><tr><td>Revisions other than price</td><td>-91</td><td>13</td><td>-78</td></tr><tr><td>Conversion to proved developed reserves</td><td>-116</td><td>-31</td><td>-147</td></tr><tr><td>Proved undeveloped reserves as of December 31, 2013</td><td>258</td><td>443</td><td>701</td></tr></table>
<table><tr><td>Operating Subsidiary:</td><td>A.M. Best</td><td>Standard & Poor's</td><td>Moody's</td></tr><tr><td>Everest Re</td><td>A+ (Superior)</td><td>A+ (Strong)</td><td>A1 (upper-medium)</td></tr><tr><td>Bermuda Re</td><td>A+ (Superior)</td><td>A+ (Strong)</td><td>A1 (upper-medium)</td></tr><tr><td>Ireland Re</td><td>A+ (Superior)</td><td>A+ (Strong)</td><td>Not Rated</td></tr><tr><td>Everest National</td><td>A+ (Superior)</td><td>A+ (Strong)</td><td>Not Rated</td></tr><tr><td>Everest Indemnity</td><td>A+ (Superior)</td><td>A+ (Strong)</td><td>Not Rated</td></tr><tr><td>Everest Security</td><td>A+ (Superior)</td><td>Not Rated</td><td>Not Rated</td></tr><tr><td>Everest International Assurance, Ltd.</td><td>A+ (Superior)</td><td>A (Strong )</td><td>Not Rated</td></tr><tr><td>Everest International</td><td>A+ (Superior)</td><td>Not Rated</td><td>Not Rated</td></tr><tr><td>Everest Canada</td><td>A+ (Superior)</td><td>Not Rated</td><td>Not Rated</td></tr><tr><td>Mt. Logan Re Ltd.</td><td>Not Rated</td><td>Not Rated</td><td>Not Rated</td></tr></table>
<table><tr><td></td><td colspan="2">A.M. Best</td><td colspan="2">Standard & Poor's</td><td colspan="2">Moody's</td></tr><tr><td>Senior Notes</td><td>a-</td><td>(Strong)</td><td>A-</td><td>(Strong)</td><td>Baa1</td><td>(Medium Grade)</td></tr><tr><td>Long Term Notes</td><td>bbb</td><td>(Adequate)</td><td>BBB</td><td>(Adequate)</td><td>Baa2</td><td>(Medium Grade)</td></tr></table>
<table><tr><td></td><td colspan="3">Years Ended December 31,</td><td colspan="2">2015/2014</td><td colspan="2">2014/2013</td></tr><tr><td>(Dollars in millions)</td><td>2015</td><td>2014</td><td>2013</td><td>Variance</td><td>% Change</td><td>Variance</td><td>% Change</td></tr><tr><td>Gross written premiums</td><td>$1,963.5</td><td>$2,039.6</td><td>$1,809.7</td><td>$-76.1</td><td>-3.7%</td><td>$229.9</td><td>12.7%</td></tr><tr><td>Net written premiums</td><td>1,855.9</td><td>1,983.8</td><td>1,807.1</td><td>-127.9</td><td>-6.4%</td><td>176.7</td><td>9.8%</td></tr><tr><td>Premiums earned</td><td>$1,952.7</td><td>$1,986.8</td><td>$1,671.5</td><td>$-34.1</td><td>-1.7%</td><td>$315.3</td><td>18.9%</td></tr><tr><td>Incurred losses and LAE</td><td>825.1</td><td>954.5</td><td>814.7</td><td>-129.4</td><td>-13.6%</td><td>139.9</td><td>17.2%</td></tr><tr><td>Commission and brokerage</td><td>493.3</td><td>466.3</td><td>366.9</td><td>27.0</td><td>5.8%</td><td>99.4</td><td>27.1%</td></tr><tr><td>Other underwriting expenses</td><td>50.1</td><td>45.6</td><td>47.2</td><td>4.5</td><td>9.9%</td><td>-1.6</td><td>-3.4%</td></tr><tr><td>Underwriting gain (loss)</td><td>$584.3</td><td>$520.4</td><td>$442.8</td><td>$63.9</td><td>12.3%</td><td>$77.6</td><td>17.5%</td></tr><tr><td></td><td></td><td></td><td></td><td></td><td>Point Chg</td><td></td><td>Point Chg</td></tr><tr><td>Loss ratio</td><td>42.3%</td><td>48.0%</td><td>48.7%</td><td></td><td>-5.7</td><td></td><td>-0.7</td></tr><tr><td>Commission and brokerage ratio</td><td>25.3%</td><td>23.5%</td><td>21.9%</td><td></td><td>1.8</td><td></td><td>1.6</td></tr><tr><td>Other underwriting expense ratio</td><td>2.5%</td><td>2.3%</td><td>2.9%</td><td></td><td>0.2</td><td></td><td>-0.6</td></tr><tr><td>Combined ratio</td><td>70.1%</td><td>73.8%</td><td>73.5%</td><td></td><td>-3.7</td><td></td><td>0.3</td></tr><tr><td>(NM, not meaningful)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td colspan="2">(Some amounts may not reconcile due to rounding.)</td><td></td><td></td><td></td><td></td><td></td><td></td></tr></table>
<table><tr><td></td><td colspan="3">At December 31,</td></tr><tr><td>(Dollars in millions)</td><td>2015</td><td>2014</td><td>2013</td></tr><tr><td>U.S. Reinsurance</td><td>$368.9</td><td>$387.2</td><td>$336.0</td></tr><tr><td>International</td><td>233.2</td><td>238.8</td><td>231.5</td></tr><tr><td>Bermuda</td><td>250.0</td><td>207.8</td><td>207.8</td></tr><tr><td>Mt. Logan</td><td>17.7</td><td>2.6</td><td>0.3</td></tr><tr><td>Total</td><td>$869.8</td><td>$836.5</td><td>$775.6</td></tr><tr><td>(Some amounts may not reconcile due to rounding.)</td><td></td><td></td><td></td></tr></table>

Question: Which year is Incurred losses and LAE greater than 900 ?