Results of Operations Revenue We generate revenue primarily from our solid waste collection operations.
Our remaining revenue is from other services, including transfer station services, landfill disposal and recycling.
Our residential and commercial collection operations in some markets are based on long-term contracts with municipalities.
Certain of our municipal contracts have annual price escalation clauses that are tied to changes in an underlying base index such as the consumer price index.
We generally provide commercial and industrial collection services to customers under contracts with terms up to three years.
Our transfer stations, landfills and, to a lesser extent, our recycling facilities generate revenue from disposal or tipping fees charged to third parties.
In general, we integrate our recycling operations with our collection operations and obtain revenue from the sale of recycled commodities.
Other non-core revenue consists primarily of revenue from National Accounts, which represents the portion of revenue generated from nationwide contracts in markets outside our operating areas where the associated waste handling services are subcontracted to local operators.
Consequently, substantially all of this revenue is offset with related subcontract costs, which are recorded in cost of operations.
The following table reflects our revenue by service line for the years ended December 31, 2014, 2013 and 2012 (in millions of dollars and as a percentage of revenue):
## Table 0 ##
The following table reflects changes in our revenue for the years ended December 31, 2014, 2013 and 2012:
## Table 1 ##
changes included reducing administrative staffing levels, relocating office space and closing certain office locations.
The savings realized from these restructuring efforts were reinvested in our customer-focused programs and initiatives.
Additionally, in the second quarter of 2016, we began the redesign of our back-office functions as well as the consolidation of over 100 customer service locations into three Customer Resource Centers.
During 2016, we incurred $40.7 million of restructuring charges that consisted of severance and other employee termination benefits, relocation benefits, and the closure of offices with lease agreements with non-cancelable terms.
We paid $32.5 million related to these restructuring efforts.
Interest Expense The following table provides the components of interest expense, including accretion of debt discounts and accretion of discounts primarily associated with environmental and risk insurance liabilities assumed in acquisitions (in millions of dollars):
## Table 2 ##
Total interest expense for 2017 decreased primarily due to the issuance of $500.0 million of 2.90% senior notes in July 2016 that were used to purchase outstanding notes and debentures with coupons ranging from 5.70% to 7.40%.
As a result of the debt that was extinguished in 2016, total interest expense for 2016 increased primarily due to $7.2 million of unamortized cash flow hedges reclassified to earnings as non-cash interest expense.
During the second half of 2013, we entered into various interest rate swap agreements relative to our 4.750% fixed rate senior notes due in May 2023.
These swap agreements, which were designated as fair value hedges, have a total notional value of $300.0 million and resulted in a $4.8 million reduction in interest expense during 2017, compared to a $6.3 million reduction in interest expense during 2016 and a $7.5 million reduction in interest expense during 2015.
During 2017, 2016 and 2015, cash paid for interest was $326.9 million, $330.2 million and $327.6 million, respectively.
Loss on Extinguishment of Debt During 2017, we retired $86.7 million of 5.25% tax-exempt bonds, resulting in a non-cash charge of $0.8 million.
During 2016, we incurred a loss on the early extinguishment of debt.
We paid a cash premium of $148.1 million, early tender consideration of $28.7 million and $1.6 million of associated legal and other fees.
We also incurred a non-cash charge related to the proportional share of unamortized discounts and deferred issuance costs of $17.8 million.
The unamortized proportional share of certain cash flow hedges reclassified to earnings as non-cash interest expense was $7.2 million.
Income Taxes Our provision for income taxes was $3.1 million, $352.7 million and $445.5 million for 2017, 2016 and 2015, respectively.
Our effective income tax rate was 0.2%, 36.5% and 37.3% for 2017, 2016 and 2015, respectively.
We made income tax payments (net of refunds received) of approximately $370 million, $265 million and $321 million for 2017, 2016 and 2015, respectively
REPUBLIC SERVICES, INC.  NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—(Continued) high quality financial institutions.
Such balances may be in excess of FDIC insured limits.
To manage the related credit exposure, we continually monitor the credit worthiness of the financial institutions where we have deposits.
Concentrations of credit risk with respect to trade accounts receivable are limited due to the wide variety of customers and markets in which we provide services, as well as the dispersion of our operations across many geographic areas.
We provide services to small-container, large-container, municipal and residential, and energy services customers in the United States and Puerto Rico.
We perform ongoing credit evaluations of our customers, but generally do not require collateral to support customer receivables.
We establish an allowance for doubtful accounts based on various factors including the credit risk of specific customers, age of receivables outstanding, historical trends, economic conditions and other information.
Accounts Receivable, Net Accounts receivable represent receivables from customers for collection, transfer, recycling, disposal, energy services and other services.
Our receivables are recorded when billed or when the related revenue is earned and represent claims against third parties that will be settled in cash.
The carrying value of our receivables, net of the allowance for doubtful accounts and customer credits, represents their estimated net realizable value.
Provisions for doubtful accounts are evaluated on a monthly basis and are recorded based on our historical collection experience, the age of the receivables, specific customer information and economic conditions.
We also review outstanding balances on an account-specific basis.
In general, reserves are provided for accounts receivable in excess of 90 days outstanding.
Past due receivable balances are written-off when our collection efforts have been unsuccessful in collecting amounts due.
The following table reflects the activity in our allowance for doubtful accounts for the years ended December 31:
## Table 3 ##
Restricted Cash and Marketable Securities As of December 31, 2018, we had $108.1 million of restricted cash and marketable securities of which $78.6 million supports our insurance programs for workers’ compensation, commercial general liability, and commercial auto liability.
Additionally, we obtain funds through the issuance of tax-exempt bonds for the purpose of financing qualifying expenditures at our landfills, transfer stations, collection and recycling processing centers.
The funds are deposited directly into trust accounts by the bonding authorities at the time of issuance.
As the use of these funds is contractually restricted, and we do not have the ability to use these funds for general operating purposes, they are classified as restricted cash and marketable securities in our consolidated balance sheets.
In the normal course of business, we may be required to provide financial assurance to governmental agencies and a variety of other entities in connection with municipal residential collection contracts, closure or postclosure of landfills, environmental remediation, environmental permits, and business licenses and permits as a financial guarantee of our performance.
At several of our landfills, we satisfy financial assurance requirements by depositing cash into restricted trust funds or escrow accounts.

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td colspan="2">2014</td><td colspan="2">2013</td><td colspan="2">2012</td></tr><tr><td>Collection:</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Residential</td><td>$2,193.6</td><td>25.0%</td><td>$2,175.5</td><td>25.8%</td><td>$2,155.7</td><td>26.6%</td></tr><tr><td>Commercial</td><td>2,723.3</td><td>31.0</td><td>2,616.9</td><td>31.1</td><td>2,523.2</td><td>31.1</td></tr><tr><td>Industrial</td><td>1,784.0</td><td>20.3</td><td>1,639.4</td><td>19.5</td><td>1,544.2</td><td>19.0</td></tr><tr><td>Other</td><td>37.2</td><td>0.4</td><td>34.7</td><td>0.4</td><td>33.4</td><td>0.4</td></tr><tr><td>Total collection</td><td>6,738.1</td><td>76.7</td><td>6,466.5</td><td>76.8</td><td>6,256.5</td><td>77.1</td></tr><tr><td>Transfer</td><td>1,062.6</td><td></td><td>1,021.8</td><td></td><td>964.5</td><td></td></tr><tr><td>Less: intercompany</td><td>-654.4</td><td></td><td>-615.2</td><td></td><td>-575.3</td><td></td></tr><tr><td>Transfer, net</td><td>408.2</td><td>4.6</td><td>406.6</td><td>4.8</td><td>389.2</td><td>4.8</td></tr><tr><td>Landfill</td><td>2,014.5</td><td></td><td>1,927.2</td><td></td><td>1,863.3</td><td></td></tr><tr><td>Less: intercompany</td><td>-928.1</td><td></td><td>-902.2</td><td></td><td>-862.5</td><td></td></tr><tr><td>Landfill, net</td><td>1,086.4</td><td>12.4</td><td>1,025.0</td><td>12.2</td><td>1,000.8</td><td>12.3</td></tr><tr><td>Sale of recycled commodities</td><td>390.8</td><td>4.4</td><td>374.6</td><td>4.5</td><td>349.0</td><td>4.3</td></tr><tr><td>Other non-core</td><td>164.8</td><td>1.9</td><td>144.5</td><td>1.7</td><td>122.8</td><td>1.5</td></tr><tr><td>Other</td><td>555.6</td><td>6.3</td><td>519.1</td><td>6.2</td><td>471.8</td><td>5.8</td></tr><tr><td>Total revenue</td><td>$8,788.3</td><td>100.0%</td><td>$8,417.2</td><td>100.0%</td><td>$8,118.3</td><td>100.0%</td></tr></table>
<table><tr><td></td><td>2014</td><td>2013</td><td>2012</td></tr><tr><td>Average yield</td><td>1.4%</td><td>1.3%</td><td>0.8%</td></tr><tr><td>Fuel recovery fees</td><td>0.1</td><td>0.3</td><td>0.1</td></tr><tr><td>Total price</td><td>1.5</td><td>1.6</td><td>0.9</td></tr><tr><td>Volume</td><td>2.0</td><td>1.3</td><td>-1.0</td></tr><tr><td>Recycled commodities</td><td>0.1</td><td>0.3</td><td>-1.2</td></tr><tr><td>Total internal growth</td><td>3.6</td><td>3.2</td><td>-1.3</td></tr><tr><td>Acquisitions / divestitures, net</td><td>0.8</td><td>0.5</td><td>0.4</td></tr><tr><td>Total</td><td>4.4%</td><td>3.7%</td><td>-0.9%</td></tr><tr><td>Core price</td><td>3.1%</td><td>3.3%</td><td>2.8%</td></tr></table>
<table><tr><td></td><td>2017</td><td>2016</td><td>2015</td></tr><tr><td>Interest expense on debt and capital lease obligations</td><td>$324.8</td><td>$324.1</td><td>$324.6</td></tr><tr><td>Accretion of debt discounts</td><td>7.6</td><td>7.6</td><td>7.4</td></tr><tr><td>Accretion of remediation liabilities and other</td><td>36.0</td><td>45.8</td><td>39.7</td></tr><tr><td>Less: capitalized interest</td><td>-6.5</td><td>-6.2</td><td>-6.8</td></tr><tr><td>Total interest expense</td><td>$361.9</td><td>$371.3</td><td>$364.9</td></tr></table>
<table><tr><td></td><td>2018</td><td>2017</td><td>2016</td></tr><tr><td>Balance at beginning of year</td><td>$38.9</td><td>$44.0</td><td>$46.7</td></tr><tr><td>Additions charged to expense</td><td>34.8</td><td>30.6</td><td>20.4</td></tr><tr><td>Accounts written-off</td><td>- 39.4</td><td>- 35.7</td><td>- 23.1</td></tr><tr><td>Balance at end of year</td><td>$34.3</td><td>$38.9</td><td>$44.0</td></tr></table>

Question: as of december 31 , 2018 what was the percentage decline in the allowance for doubtful accounts
Answer: -0.11825
Reasoning program: subtract(34.3,38.9), divide(#0,38.9)