Table XVII Quarterly Reconciliations to GAAP Financial Measures (1) (continued)
## Table 0 ##
For footnotes see page 139.
Cash and Cash Equivalents Cash equivalents include highly-liquid investments with a maturity of three months or less when purchased.
Accounts Receivable and Allowance For Doubtful Accounts Accounts receivable are carried at the invoiced amounts, less an allowance for doubtful accounts, and generally do not bear interest.
The Company estimates the balance of allowance for doubtful accounts by analyzing accounts receivable balances by age and applying historical write-off and collection trend rates.
The Company’s estimates include separately providing for customer receivables based on specific circumstances and credit conditions, and when it is deemed probable that the balance is uncollectible.
Account balances are written off against the allowance when it is determined the receivable will not be recovered.
The Company’s allowance for doubtful accounts balance also includes an allowance for the expected return of products shipped and credits related to pricing or quantities shipped of $15 million, $14 million and $15 million as of December 31, 2017, 2016, and 2015, respectively.
Returns and credit activity is recorded directly to sales as a reduction.
The following table summarizes the activity in the allowance for doubtful accounts:
## Table 1 ##
(a) Other amounts are primarily the effects of changes in currency translations and the impact of allowance for returns and credits.
Inventory Valuations Inventories are valued at the lower of cost or net realizable value.
Certain U. S.  inventory costs are determined on a last-in, first-out (“LIFO”) basis.
LIFO inventories represented 39% and 40% of consolidated inventories as of December 31, 2017 and 2016, respectively.
All other inventory costs are determined using either the average cost or first-in, first-out (“FIFO”) methods.
Inventory values at FIFO, as shown in Note 5, approximate replacement cost.
Property, Plant and Equipment Property, plant and equipment assets are stated at cost.
Merchandising and customer equipment consists principally of various dispensing systems for the Company’s cleaning and sanitizing products, dishwashing machines and process control and monitoring equipment.
Certain dispensing systems capitalized by the Company are accounted for on a mass asset basis, whereby equipment is capitalized and depreciated as a group and written off when fully depreciated.
The Company capitalizes both internal and external costs of development or purchase of computer software for internal use.
Costs incurred for data conversion, training and maintenance associated with capitalized software are expensed as incurred.
Expenditures for major renewals and improvements, which significantly extend the useful lives of existing plant and equipment, are capitalized and depreciated.
Expenditures for repairs and maintenance are charged to expense as incurred.
Upon retirement or disposition of plant and equipment, the cost and related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized in income.
Depreciation is charged to operations using the straight-line method over the assets’ estimated useful lives ranging from 5 to 40 years for buildings and leasehold improvements, 3 to 20 years for machinery and equipment, 3 to 15 years for merchandising and customer equipment and 3 to 7 years for capitalized software.
The straight-line method of depreciation reflects an appropriate allocation of the cost of the assets to earnings in proportion to the amount of economic benefits obtained by the Company in each reporting period.
Depreciation expense was $586 million, $561 million and $560 million for 2017, 2016 and 2015, respectively.
16.
Other (Income) Expense, Net
## Table 2 ##
The decline in interest income and increase in interest expense in 2010 as compared with 2009 is largely attributable to the Merger.
The increase in exchange losses during 2010 is primarily due to the recognition of $200 million of exchange losses due to two Venezuelan currency devaluations as discussed below.
The change in Other, net (as presented in the table above) for 2010 as compared with 2009 primarily reflects a $7.5 billion gain in 2009 resulting from recognizing Merck’s previously held equity interest in the MSP Partnership at fair value as a result of obtaining control of the MSP Partnership in the Merger (see Note 3), a $3.2 billion gain in 2009 on the sale of Old Merck’s interest in Merial (see Note 10), a $950 million charge for the Vioxx Liability Reserve recorded in 2010 (see Note 12), lower recognized net gains in 2010 on the Company’s investment portfolio and charges recognized in 2010 related to the settlement of certain pending AWP litigation (see Note 12).
These items were partially offset by $443 million of income recognized upon AstraZeneca’s asset option exercise (see Note 10) and $102 million of income recognized on the settlement of certain disputed royalties in 2010.
Effective January 1, 2010, the Company was required to remeasure its local currency operations in Venezuela to U. S.  dollars as the Venezuelan economy was determined to be hyperinflationary.
Effective January 11, 2010, the Venezuelan government devalued its currency from at BsF 2.15 per U. S.  dollar to a two-tiered official exchange rate at (1) “the essentials rate” at BsF 2.60 per U. S.  dollar and (2) “the non-essentials rate” at BsF 4.30 per U. S.  dollar.
Throughout 2010, the Company settled transactions at the essentials rate and therefore remeasured monetary assets and liabilities utilizing the essentials rate.
In December 2010, the Venezuelan government announced it would eliminate the essentials rate and effective January 1, 2011, all transactions would be settled at the official rate of at BsF 4.30 per U. S.  dollar.
As a result of this announcement, the Company remeasured its December 31, 2010 monetary assets and liabilities at the new official rate.
The decline in interest income in 2009 as compared with 2008 is primarily the result of lower interest rates and a change in the investment portfolio mix toward cash and shorter-dated securities in anticipation of the Merger.
The increase in interest expense in 2009 is largely due to $173 million of commitment fees and incremental interest expense related to the financing of the Merger.
Included in Other, net in 2009 was the $7.5 billion gain as a result of obtaining control of the MSP Partnership in the Merger, the $3.2 billion gain on the sale of Old Merck’s interest in Merial, $231 million of investment portfolio recognized net gains, and an $80 million charge related to the settlement of the Vioxx third-party payor litigation in the United States.
Included in Other, net in 2008 was an aggregate gain on distribution from AZLP of $2.2 billion (see Note 10), a gain of $249 million related to the sale of the remaining worldwide rights to Aggrastat, a $300 million expense for a contribution to the Merck Company Foundation and $117 million of investment portfolio recognized net losses.
Interest paid was $763 million in 2010, $351 million in 2009, $247 million in 2008, which excludes commitment fees.

<table><tr><td></td><td colspan="4">2011 Quarters</td><td colspan="4">2010 Quarters</td></tr><tr><td>(Dollars in millions, except per share information)</td><td>Fourth</td><td>Third</td><td>Second</td><td>First</td><td>Fourth</td><td>Third</td><td>Second</td><td>First</td></tr><tr><td>Reconciliation of average shareholders’ equity to average tangible shareholders’ equity</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Shareholders’ equity</td><td>$228,235</td><td>$222,410</td><td>$235,067</td><td>$230,769</td><td>$235,525</td><td>$233,978</td><td>$233,461</td><td>$229,891</td></tr><tr><td>Goodwill</td><td>-70,647</td><td>-71,070</td><td>-73,748</td><td>-73,922</td><td>-75,584</td><td>-82,484</td><td>-86,099</td><td>-86,334</td></tr><tr><td>Intangible assets (excluding MSRs)</td><td>-8,566</td><td>-9,005</td><td>-9,394</td><td>-9,769</td><td>-10,211</td><td>-10,629</td><td>-11,216</td><td>-11,906</td></tr><tr><td>Related deferred tax liabilities</td><td>2,775</td><td>2,852</td><td>2,932</td><td>3,035</td><td>3,121</td><td>3,214</td><td>3,395</td><td>3,497</td></tr><tr><td>Tangible shareholders’ equity</td><td>$151,797</td><td>$145,187</td><td>$154,857</td><td>$150,113</td><td>$152,851</td><td>$144,079</td><td>$139,541</td><td>$135,148</td></tr><tr><td>Reconciliation of period-end common shareholders’ equity to period-end tangible common shareholders’ equity</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Common shareholders’ equity</td><td>$211,704</td><td>$210,772</td><td>$205,614</td><td>$214,314</td><td>$211,686</td><td>$212,391</td><td>$215,181</td><td>$211,859</td></tr><tr><td>Goodwill</td><td>-69,967</td><td>-70,832</td><td>-71,074</td><td>-73,869</td><td>-73,861</td><td>-75,602</td><td>-85,801</td><td>-86,305</td></tr><tr><td>Intangible assets (excluding MSRs)</td><td>-8,021</td><td>-8,764</td><td>-9,176</td><td>-9,560</td><td>-9,923</td><td>-10,402</td><td>-10,796</td><td>-11,548</td></tr><tr><td>Related deferred tax liabilities</td><td>2,702</td><td>2,777</td><td>2,853</td><td>2,933</td><td>3,036</td><td>3,123</td><td>3,215</td><td>3,396</td></tr><tr><td>Tangible common shareholders’ equity</td><td>$136,418</td><td>$133,953</td><td>$128,217</td><td>$133,818</td><td>$130,938</td><td>$129,510</td><td>$121,799</td><td>$117,402</td></tr><tr><td>Reconciliation of period-end shareholders’ equity to period-end tangible shareholders’ equity</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Shareholders’ equity</td><td>$230,101</td><td>$230,252</td><td>$222,176</td><td>$230,876</td><td>$228,248</td><td>$230,495</td><td>$233,174</td><td>$229,823</td></tr><tr><td>Goodwill</td><td>-69,967</td><td>-70,832</td><td>-71,074</td><td>-73,869</td><td>-73,861</td><td>-75,602</td><td>-85,801</td><td>-86,305</td></tr><tr><td>Intangible assets (excluding MSRs)</td><td>-8,021</td><td>-8,764</td><td>-9,176</td><td>-9,560</td><td>-9,923</td><td>-10,402</td><td>-10,796</td><td>-11,548</td></tr><tr><td>Related deferred tax liabilities</td><td>2,702</td><td>2,777</td><td>2,853</td><td>2,933</td><td>3,036</td><td>3,123</td><td>3,215</td><td>3,396</td></tr><tr><td>Tangible shareholders’ equity</td><td>$154,815</td><td>$153,433</td><td>$144,779</td><td>$150,380</td><td>$147,500</td><td>$147,614</td><td>$139,792</td><td>$135,366</td></tr><tr><td>Reconciliation of period-end assets to period-end tangible assets</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Assets</td><td>$2,129,046</td><td>$2,219,628</td><td>$2,261,319</td><td>$2,274,532</td><td>$2,264,909</td><td>$2,339,660</td><td>$2,368,384</td><td>$2,344,634</td></tr><tr><td>Goodwill</td><td>-69,967</td><td>-70,832</td><td>-71,074</td><td>-73,869</td><td>-73,861</td><td>-75,602</td><td>-85,801</td><td>-86,305</td></tr><tr><td>Intangible assets (excluding MSRs)</td><td>-8,021</td><td>-8,764</td><td>-9,176</td><td>-9,560</td><td>-9,923</td><td>-10,402</td><td>-10,796</td><td>-11,548</td></tr><tr><td>Related deferred tax liabilities</td><td>2,702</td><td>2,777</td><td>2,853</td><td>2,933</td><td>3,036</td><td>3,123</td><td>3,215</td><td>3,396</td></tr><tr><td>Tangible assets</td><td>$2,053,760</td><td>$2,142,809</td><td>$2,183,922</td><td>$2,194,036</td><td>$2,184,161</td><td>$2,256,779</td><td>$2,275,002</td><td>$2,250,177</td></tr></table>
<table><tr><td>(millions)</td><td>2017</td><td>2016</td><td>2015</td></tr><tr><td>Beginning balance</td><td>$67.6</td><td>$75.3</td><td>$77.5</td></tr><tr><td>Bad debt expense</td><td>17.1</td><td>20.1</td><td>25.8</td></tr><tr><td>Write-offs</td><td>-15.7</td><td>-24.6</td><td>-21.9</td></tr><tr><td>Other (a)</td><td>2.5</td><td>-3.2</td><td>-6.1</td></tr><tr><td>Ending balance</td><td>$71.5</td><td>$67.6</td><td>$75.3</td></tr></table>
<table><tr><td><i>Years Ended December 31</i></td><td>2010</td><td>2009</td><td>2008</td></tr><tr><td>Interest income</td><td>$-83</td><td>$-210</td><td>$-631</td></tr><tr><td>Interest expense</td><td>715</td><td>460</td><td>251</td></tr><tr><td>Exchange losses (gains)</td><td>214</td><td>-12</td><td>147</td></tr><tr><td>Other, net</td><td>458</td><td>-10,906</td><td>-2,085</td></tr><tr><td></td><td>$1,304</td><td>$-10,668</td><td>$-2,318</td></tr></table>

Question: what is the percentage change in the balance of allowance for doubtful accounts from 2016 to 2017?