Overall, billed business increased in 2017 compared to 2016.
U. S.  billed business increased 1 percent and non-U.
S.  billed business increased 12 percent.
See Tables 5 and 6 for more details on billed business performance.
The average discount rate was 2.43 percent, 2.45 percent and 2.46 percent for 2017, 2016 and 2015, respectively.
The decrease in the average discount rate in 2017 compared to 2016 primarily reflected rate pressure from merchant negotiations, including those resulting from the recent regulatory changes affecting competitor pricing in certain international markets, the continued growth of the OptBlue program, and changes in industry and geographic mix.
We expect the average discount rate will continue to decline over time due to a greater shift of existing merchants into OptBlue, merchant negotiations and competition, volume related pricing discounts, certain pricing initiatives mainly driven by pricing regulation (including regulation of competitors’ interchange rates) and other factors.
Net card fees increased in both periods.
The increase in 2017 was primarily driven by growth in the Platinum and Delta portfolios and growth in key international markets.
The increase in 2016 was primarily driven by growth in the Platinum, Gold and Delta portfolios.
Other fees and commissions increased in 2017 compared to 2016, and decreased in 2016 compared to 2015.
The increase in 2017 was primarily driven by an increase in delinquency fees due to a change in the late fee assessment date for certain U. S.  charge cards and an increase in foreign exchange conversion revenue.
The decrease in 2016 was primarily due to lower Costco-related fees, partially offset by an increase in delinquency and loyalty coalition-related fees.
Other revenues decreased in 2017 compared to 2016, and were relatively flat in 2016 compared to 2015.
The decrease in 2017 was primarily driven by prior-year revenues related to the Loyalty Edge business, which was sold in the fourth quarter of 2016, and a contractual payment from a GNS partner also in the prior year.2016 included the previously-mentioned contractual payment from a GNS partner and higher revenues from our Prepaid Services business compared to 2015, offset by lower revenues related to Costco, Loyalty Edge and the GBT JV transition services agreement.
Interest income increased in 2017 compared to 2016 and decreased in 2016 compared to 2015.
The increase in 2017 primarily reflected higher average Card Member loans and higher yields.
The growth in average Card Member loans was primarily driven by a mix shift over time towards non-cobrand lending products, where Card Members tend to revolve more of their loan balances.
The increase in yields was primarily driven by a greater percentage of loans at higher rate buckets, specific pricing actions, and increases in benchmark interest rates.
The decrease in 2016 was primarily driven by lower Costco cobrand loans and the associated interest income, partially offset by modestly higher yields and an increase in average Card Member loans across other lending products.
Interest expense increased in both periods.
The increase in 2017 was primarily driven by higher interest rates and higher average long-term debt.
The increase in 2016 was primarily driven by higher average customer deposit balances, partially offset by lower average long-term debt.
TABLE 3: PROVISIONS FOR LOSSES SUMMARY
## Table 0 ##
(a) Beginning December 1, 2015 through to the sale completion dates, did not reflect the HFS portfolios.
EXPENSES Marketing, promotion, rewards, Card Member services and other expenses increased in 2017 compared to 2016, reflecting higher Card Member rewards and Card Member services and other expenses, partially offset by lower marketing and promotion expenses.
Card Member rewards expense increased $218 million, primarily driven by enhancements to Platinum rewards and increased spending volumes, partially offset by Costco-related expenses in the prior year.
Card Member services and other expense increased $173 million driven by higher usage of travel-related benefits and enhanced Platinum card benefits.
Marketing and promotion expenses decreased $112 million due to lower spending on growth initiatives.
Salaries and employee benefits and other operating expense increased in 2017 compared to 2016, primarily reflecting the gains on the sales of the HFS portfolios in the prior year, which were recognized as an expense reduction in other expenses, partially offset by lower technology and other servicing-related costs in the current year and restructuring charges in the prior year.
Total expenses decreased in 2016 compared to 2015, primarily driven by lower salaries and employee benefits and other operating expenses, largely reflecting the gains on the sales of the HFS portfolios as previously mentioned.
Income tax provision decreased in 2017 compared to 2016, primarily reflecting the impact of recurring permanent tax benefits on the lower level of pretax income.
## Table 1 ##
(a) Refer to Table 7 footnote (a).
(b) Refer to Table 7 footnote (e).
(c) Refer to Table 8 footnote (a).
(d) Refer to Table 8 footnote (b).
(e) Refer to Table 8 footnote (c).
(f) Refer to Table 8 footnote (d).
UNITED PARCEL SERVICE, INC.  AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—(Continued) The following table summarizes the activity related to our unrecognized tax benefits (in millions):
## Table 2 ##
As of December 31, 2007, the total amount of gross unrecognized tax benefits that, if recognized, would affect the effective tax rate was $134 million.
We also had gross recognized tax benefits of $567 million recorded as of December 31, 2007 associated with outstanding refund claims for prior tax years.
Therefore, we had a net receivable recorded with respect to prior year income tax matters in the accompanying balance sheets.
Our continuing practice is to recognize interest and penalties associated with income tax matters as a component of income tax expense.
Related to the uncertain tax benefits noted above, we accrued penalties of $5 million and interest of $36 million during 2007.
As of December 31, 2007, we have recognized a liability for penalties of $6 million and interest of $75 million.
Additionally, we have recognized a receivable for interest of $116 million for the recognized tax benefits associated with outstanding refund claims.
We file income tax returns in the U. S.  federal jurisdiction, most U. S.  state and local jurisdictions, and many non-U.
S.  jurisdictions.
As of December 31, 2007, we had substantially resolved all U. S.  federal income tax matters for tax years prior to 1999.
In the third quarter of 2007, we entered into a Joint Stipulation to Dismiss the case with the Department of Justice, effectively withdrawing our refund claim related to the 1994 disposition of a subsidiary in France.
The write-off of previously recognized tax receivable balances associated with the 1994 French matter resulted in a $37 million increase in income tax expense for the quarter.
However, this increase was offset by the impact of favorable developments with various other U. S.  federal, U. S.  state, and non-U.
S.  contingency matters.
In February 2008, the IRS completed its audit of the tax years 1999 through 2002 with only a limited number of issues that will be considered by the IRS Appeals Office by 2009.
The IRS is in the final stages of completing its audit of the tax years 2003 through 2004.
We anticipate that the IRS will conclude its audit of the 2003 and 2004 tax years by 2009.
With few exceptions, we are no longer subject to U. S.  state and local and non-U.
S.  income tax examinations by tax authorities for tax years prior to 1999, but certain U. S.  state and local matters are subject to ongoing litigation.
A number of years may elapse before an uncertain tax position is audited and ultimately settled.
It is difficult to predict the ultimate outcome or the timing of resolution for uncertain tax positions.
It is reasonably possible that the amount of unrecognized tax benefits could significantly increase or decrease within the next twelve months.
Items that may cause changes to unrecognized tax benefits include the timing of interest deductions, the deductibility of acquisition costs, the consideration of filing requirements in various states, the allocation of income and expense between tax jurisdictions and the effects of terminating an election to have a foreign subsidiary join in filing a consolidated return.
These changes could result from the settlement of ongoing litigation, the completion of ongoing examinations, the expiration of the statute of limitations, or other unforeseen circumstances.
At this time, an estimate of the range of the reasonably possible change cannot be made.

Tables referenced above, in order (Table 0 first):
<table><tr><td>Years Ended December 31,</td><td></td><td></td><td></td><td colspan="2" rowspan="2"Change 2017 vs. 2016></td><td colspan="2" rowspan="2"Change 2016 vs. 2015></td></tr><tr><td>(Millions, except percentages)</td><td>2017</td><td>2016</td><td>2015</td></tr><tr><td>Charge card</td><td>$795</td><td>$696</td><td>$737</td><td>$99</td><td>14%</td><td>$-41</td><td>-6%</td></tr><tr><td>Card Member loans</td><td>1,868</td><td>1,235</td><td>1,190</td><td>633</td><td>51</td><td>45</td><td>4</td></tr><tr><td>Other</td><td>96</td><td>95</td><td>61</td><td>1</td><td>1</td><td>34</td><td>56</td></tr><tr><td>Total provisions for losses<sup>(a)</sup></td><td>$2,759</td><td>$2,026</td><td>$1,988</td><td>$733</td><td>36%</td><td>$38</td><td>2%</td></tr></table>
<table><tr><td>As of or for the Years Ended December 31,</td><td></td><td></td><td></td><td rowspan="2">Change 2017 vs. 2016</td><td rowspan="2">Change 2016 vs. 2015</td></tr><tr><td>(Millions, except percentages and where indicated)</td><td>2017</td><td>2016</td><td>2015</td></tr><tr><td>Card billed business(billions)</td><td>$337.0</td><td>$345.3</td><td>$370.1</td><td>-2%</td><td>-7%</td></tr><tr><td>Charge card billed business as a % of total</td><td>36.4%</td><td>34.7%</td><td>32.4%</td><td></td><td></td></tr><tr><td>Total cards-in-force</td><td>34.9</td><td>32.7</td><td>40.7</td><td>7</td><td>-20</td></tr><tr><td>Basic cards-in-force</td><td>25.0</td><td>23.3</td><td>28.6</td><td>7</td><td>-19</td></tr><tr><td>Average basic Card Member spending(dollars)</td><td>$13,950</td><td>$13,447</td><td>$13,441</td><td>4</td><td>―</td></tr><tr><td>Total segment assets(billions)</td><td>$94.2</td><td>$87.4</td><td>$92.7</td><td>8</td><td>-6</td></tr><tr><td>Card Member loans:<sup>(a)</sup></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Total loans(billions)</td><td>$53.7</td><td>$48.8</td><td>$43.5</td><td>10</td><td>12</td></tr><tr><td>Average loans(billions)</td><td>$48.9</td><td>$44.4</td><td>$51.1</td><td>10%</td><td>-13%</td></tr><tr><td>Net write-off rate — principal only<sup>(b)</sup></td><td>1.8%</td><td>1.5%</td><td>1.4%</td><td></td><td></td></tr><tr><td>Net write-off rate — principal, interest and fees<sup>(b)</sup></td><td>2.1%</td><td>1.8%</td><td>1.6%</td><td></td><td></td></tr><tr><td>30+ days past due loans as a % of total</td><td>1.3%</td><td>1.1%</td><td>1.0%</td><td></td><td></td></tr><tr><td>Calculation of Net Interest Yield on Average Card Member loans:</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Net interest income</td><td>$5,013</td><td>$4,546</td><td>$4,710</td><td></td><td></td></tr><tr><td>Exclude:</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Interest expense not attributable to our Card Member loan portfolio<sup>(c)</sup></td><td>120</td><td>80</td><td>72</td><td></td><td></td></tr><tr><td>Interest income not attributable to our Card Member loan portfolio<sup>(d)</sup></td><td>-101</td><td>-24</td><td>-15</td><td></td><td></td></tr><tr><td>Adjusted net interest income<sup>(e)</sup></td><td>$5,032</td><td>$4,602</td><td>$4,767</td><td></td><td></td></tr><tr><td>Average Card Member loans including HFS loan portfolios(billions)<sup>(f)</sup></td><td>$48.9</td><td>$49.4</td><td>$52.1</td><td></td><td></td></tr><tr><td>Net interest income divided by average Card Member loans</td><td>10.3%</td><td>9.2%</td><td>9.0%</td><td></td><td></td></tr><tr><td>Net interest yield on average Card Member loans<sup>(e)</sup></td><td>10.3%</td><td>9.3%</td><td>9.2%</td><td></td><td></td></tr><tr><td>Card Member receivables:<sup>(a)</sup></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Total receivables(billions)</td><td>$13.1</td><td>$12.3</td><td>$11.8</td><td>7%</td><td>4%</td></tr><tr><td>Net write-off rate — principal only<sup>(b)</sup></td><td>1.3%</td><td>1.4%</td><td>1.6%</td><td></td><td></td></tr><tr><td>Net write-off rate — principal and fees<sup>(b)</sup></td><td>1.4%</td><td>1.6%</td><td>1.8%</td><td></td><td></td></tr><tr><td>30+ days past due as a % of total</td><td>1.1%</td><td>1.2%</td><td>1.4%</td><td></td><td></td></tr></table>
<table><tr><td>Balance at January 1, 2007</td><td>$373</td></tr><tr><td>Additions for tax positions of the current year</td><td>13</td></tr><tr><td>Additions for tax positions of prior years</td><td>34</td></tr><tr><td>Reductions for tax positions of prior years for:</td><td></td></tr><tr><td>Changes in judgment or facts</td><td>-12</td></tr><tr><td>Settlements during the period</td><td>-49</td></tr><tr><td>Lapses of applicable statute of limitations</td><td>-4</td></tr><tr><td>Balance at December 31, 2007</td><td>$355</td></tr></table>

Question: How many years does total loans in terms of Card Member loans keep growing?
Answer: 2