?
Fuel Prices – Crude oil prices increased at a steady rate in 2007, rising from a low of $56.58 per barrel in January to close at nearly $96.00 per barrel at the end of December.
Our 2007 average fuel price increased by 9% and added $242 million of operating expenses compared to 2006.
Our fuel surcharge programs are designed to help offset the impact of higher fuel prices.
In addition, our fuel conservation efforts allowed us to improve our consumption rate by 2%.
Locomotive simulator training, operating practices, and technology all contributed to this improvement, saving approximately 21 million gallons of fuel in 2007.  ?
Free Cash Flow – Cash generated by operating activities totaled a record $3.3 billion, yielding free cash flow of $487 million in 2007.
Free cash flow is defined as cash provided by operating activities, less cash used in investing activities and dividends paid.
Free cash flow is not considered a financial measure under accounting principles generally accepted in the United States (GAAP) by SEC Regulation G and Item 10 of SEC Regulation S-K.  We believe free cash flow is important in evaluating our financial performance and measures our ability to generate cash without additional external financings.
Free cash flow should be considered in addition to, rather than as a substitute for, cash provided by operating activities.
The following table reconciles cash provided by operating activities (GAAP measure) to free cash flow (non-GAAP measure):
## Table 0 ##
2008 Outlook ?
Safety – Operating a safe railroad benefits our employees, our customers, our shareholders, and the public.
We will continue using a multi-faceted approach to safety, utilizing technology, risk assessment, quality control, and training for, and engaging with our employees.
We plan to implement Total Safety Culture (TSC) throughout our operations.
TSC, an employee-focused initiative that has helped improve safety, is a process designed to establish, maintain, and promote safety among co-workers.
With respect to public safety, we will continue our efforts to maintain, upgrade, and close crossings, install video cameras on locomotives, and educate the public about crossing safety through various internal and industry programs, along with other activities.  ?
Commodity Revenue – Despite uncertainty regarding the U. S.  economy, we expect record revenue in 2008 based on current economic indicators, forecasted demand, improved customer service, and additional opportunities to reprice certain of our business.
Yield increases and fuel surcharges will be the primary drivers of commodity revenue growth in 2008.
We expect that overall volume will fall within a range of 1% higher to 1% lower than 2007, with continued softness in some market sectors.  ?
Transportation Plan – In 2008, we will continue to evaluate traffic flows and network logistic patterns to identify additional opportunities to simplify operations and improve network efficiency and asset utilization.
We plan to maintain adequate manpower and locomotives, improve productivity using industrial engineering techniques, and improve our operating margins.  ?
Fuel Prices – Fuel prices should remain volatile, with crude oil prices and conversion and regional spreads fluctuating throughout the year.
On average, we expect fuel prices to increase 15% to 20% above the average price in 2007.
To reduce the impact of fuel price on earnings, we will continue to seek recovery from our customers through our fuel surcharge programs and expand our fuel conservation efforts.
through 2002, among other things, resulted in the $118 million reduction in 2005.
Our effective tax rate was 36.4% and 28.6% in 2006 and 2005, respectively.
OTHER OPERATING/PERFORMANCE AND FINANCIAL STATISTICS We report key Railroad performance measures weekly to the Association of American Railroads (AAR), including carloads, average daily inventory of rail cars on our system, average train speed, and average terminal dwell time.
We provide this data on our website at www.
up.
com/investors/reports/index.
shtml.
Operating/Performance Statistics Railroad performance measures reported to the AAR, as well as other performance measures, are included in the table below:
## Table 1 ##
Average Train Speed – Average train speed is calculated by dividing train miles by hours operated on our main lines between terminals.
Ongoing network management initiatives and capacity expansion contributed to 2% and 1% improvements of average train speed during 2007 and 2006, respectively.
Average Terminal Dwell Time – Average terminal dwell time is the average time that a rail car spends at our terminals.
Lower average terminal dwell time is favorable.
Average terminal dwell improved 8% and 5% in 2007 and 2006, respectively, as a result of ongoing management initiatives and directed efforts to more timely deliver rail cars to our interchange partners and customers.
Average terminal dwell time was also impacted by 1% lower volume levels in 2007 and a 3% increase in volume levels during 2006.
Gross and Revenue Ton-Miles – Gross ton-miles are calculated by multiplying the weight of loaded or empty freight cars by the number of miles hauled.
Revenue ton-miles are calculated by multiplying the weight of freight by the number of tariff miles.
Revenue ton-miles declined 1% in relation to the 1% reduction in carloadings in 2007 compared to 2006.
Gross ton-miles decreased 2% in 2007 driven by a mix shift in freight shipments.
In 2006, gross and revenue-ton miles grew 3% in relation to the 3% increase in carloadings as volume was balanced between the higher and lower density commodities.
Operating Ratio – Operating ratio is defined as our operating expenses as a percentage of revenue.
Our operating ratio improved 2.2 points to 79.3% in 2007 as a result of yield increases, network management initiatives, and improved productivity.
In 2006, our operating ratio improved 5.3 points to 81.5% as a result of solid demand, yield increases, and improved operational efficiency.
Average Full-Time-Equivalent Employees – Lower employee levels in 2007 versus 2006 resulted from fewer train and engine personnel due to improved network productivity and 1% lower volume levels, partially offset by more employees maintaining our larger locomotive fleet.
The larger full-time-equivalent number in 2006, included more people to maintain our larger locomotive and freight car fleet, more employees needed for increased track repair and maintenance programs, more operations management personnel (including an expanded management training program), and more train and engine personnel to meet demand levels.
payables that were reclassified as part of our capital lease obligations.
Capital lease obligations are reported in our Consolidated Statements of Financial Position as debt.
On October 15, 2009, we entered into a capital lease agreement for 44 locomotives with a total equipment cost of $100 million.
The lessor purchased the 44 locomotives from the Corporation and subsequently leased the locomotives back to the Railroad.
These capital lease obligations are reported in our Consolidated Statements of Financial Position as debt at December 31, 2009.
Off-Balance Sheet Arrangements, Contractual Obligations, and Commercial Commitments As described in the notes to the Consolidated Financial Statements and as referenced in the tables below, we have contractual obligations and commercial commitments that may affect our financial condition.
Based on our assessment of the underlying provisions and circumstances of our contractual obligations and commercial commitments, including material sources of off-balance sheet and structured finance arrangements, other than the risks that we and other similarly situated companies face with respect to the condition of the capital markets (as described in Item 1A of Part II of this report), there is no known trend, demand, commitment, event, or uncertainty that is reasonably likely to occur that would have a material adverse effect on our consolidated results of operations, financial condition, or liquidity.
In addition, our commercial obligations, financings, and commitments are customary transactions that are similar to those of other comparable corporations, particularly within the transportation industry.
The following tables identify material obligations and commitments as of December 31, 2009:
## Table 2 ##
[a] Excludes capital lease obligations of $2,061 million, unamortized discount of $(110) million, and market value adjustments of $15 million for debt with qualifying hedges that are recorded as liabilities on the Consolidated Statements of Financial Position.
Includes an interest component of $4,763 million.
[b] Represents total obligations, including interest component of $914 million.
[c] Purchase obligations include locomotive maintenance contracts; purchase commitments for ties, ballast, and rail; and agreements to purchase other goods and services.
For amounts where we can not reasonably estimate the year of settlement, they are reflected in the Other column.
[d] Includes estimated other post retirement, medical, and life insurance payments and payments made under the unfunded pension plan for the next ten years.
No amounts are included for funded pension as no contributions are currently required.
[e] Future cash flows for income tax contingencies reflect the recorded liability for unrecognized tax benefits, including interest and penalties, as of December 31, 2009.
Where we can reasonably estimate the years in which these liabilities may be settled, this is shown in the table.
For amounts where we can not reasonably estimate the year of settlement, they are reflected in the Other column.
Item 7.
Management’s Discussion and Analysis of Financial Condition and Results of Operations The following discussion should be read in conjunction with the Consolidated Financial Statements and applicable notes to the Financial Statements and Supplementary Data, Item 8, and other information in this report, including Risk Factors set forth in Item 1A and Critical Accounting Policies and Cautionary Information at the end of this Item 7.
The Railroad, along with its subsidiaries and rail affiliates, is our one reportable business segment.
Although revenue is analyzed by commodity, we analyze the net financial results of the Railroad as one segment due to the integrated nature of the rail network.
EXECUTIVE SUMMARY 2017 Results ?
Safety – During 2017, we continued our focus on safety to reduce risk and eliminate incidents for our employees, our customers and the public.
We finished 2017 with a 3% improvement in our reportable derailment incident rate per million train miles compared to 2016.
Although reportable personal injury incidents per 200,000 employee-hours increased 5% from last year’s record low, it is our second lowest year and a 9% decrease from 2015.
Despite our efforts in 2017, our crossing incidents rate increased 5% from 2016.
Overall, our 2017 safety results reflect our employees’ dedication to our safety initiatives and our efforts to further engage the workforce through programs such as Courage to Care, Total Safety Culture, and UP Way (our continuous improvement culture).  ?
Network Operations – Our average train speed, as reported to the AAR, decreased 5% compared to 2016, and our average terminal dwell time increased 8% from 2016.
Disruptions across our network, including the impact of Hurricane Harvey, negatively impacted network fluidity.
Continued implementation and testing of Positive Train Control across a growing number of routes in our network also negatively impacted overall average train speed and terminal dwell.
Network operational challenges in the latter part of the year also negatively impacted terminal dwell.  ?
Tax Reform – The Tax Cuts and Jobs Act (the “Tax Act”) was enacted on December 22, 2017.
The Tax Act reduced the federal income tax rate from 35% to 21% effective January 1, 2018.
As a result, we remeasured our deferred tax assets and liabilities which resulted in a $5.9 billion non-cash reduction in our income tax expense in 2017.
In addition, we recognized a $212 million non-cash reduction to operating expense related to income tax adjustments recognized at certain equity-method affiliates.
See Note 8 of the Consolidated Financial Statements for additional information.
For comparability purposes, the following table reconciles our full year 2017 reported results under accounting principles generally accepted in the U. S.  (GAAP) to our 2017 adjusted results (non-GAAP) for the tax related items described above.
We believe the adjusted results provide relevant information to our investors as they more accurately reflect on-going financial performance.
In addition, these measures should be considered in addition to, and not a substitute for operating income, income taxes, net income, diluted EPS, operating ratio, and effective tax rate.

<table><tr><td><i>Millions of Dollars</i></td><td>2007</td><td>2006</td><td>2005</td></tr><tr><td>Cash provided by operating activities</td><td>$3,277</td><td>$2,880</td><td>$2,595</td></tr><tr><td>Cash used in investing activities</td><td>-2,426</td><td>-2,042</td><td>-2,047</td></tr><tr><td>Dividends paid</td><td>-364</td><td>-322</td><td>-314</td></tr><tr><td>Free cash flow</td><td>$487</td><td>$516</td><td>$234</td></tr></table>
<table><tr><td></td><td><i></i> <i>2007</i><i></i></td><td><i>2006</i></td><td><i>2005</i></td><td>% Change 2007 v 2006</td><td>% Change 2006 v 2005</td></tr><tr><td>Avg. train speed (miles per hour)</td><td> 21.8</td><td>21.4</td><td>21.1</td><td>2%</td><td>1%</td></tr><tr><td>Avg. terminal dwell time (hours)</td><td> 25.1</td><td>27.2</td><td>28.7</td><td>-8%</td><td>-5%</td></tr><tr><td>Gross ton-miles (billions)</td><td> 1,052.3</td><td>1,072.5</td><td>1,043.9</td><td>-2%</td><td>3%</td></tr><tr><td>Revenue ton-miles (billions)</td><td> 561.8</td><td>565.2</td><td>548.8</td><td>-1%</td><td>3%</td></tr><tr><td>Operating ratio</td><td> 79.3</td><td>81.5</td><td>86.8</td><td>2.2pt</td><td>5.3pt</td></tr><tr><td>Avg. full-time-equivalent employees</td><td> 50,089</td><td>50,739</td><td>49,747</td><td>-1%</td><td>2%</td></tr><tr><td>Customer satisfaction index</td><td> 79</td><td>72</td><td>64</td><td>7pt</td><td>8pt</td></tr></table>
<table><tr><td></td><td></td><td colspan="7"><i>Payments Due by December 31,</i></td></tr><tr><td>  <i>Contractual Obligations</i> <i>Millions of Dollars</i></td><td><i>Total</i></td><td><i>2010</i></td><td><i>2011</i></td><td><i>2012</i></td><td><i>2013</i></td><td><i>2014</i></td><td><i>After 2014</i></td><td><i>Other</i></td></tr><tr><td>Debt [a]</td><td>$12,645</td><td>$846</td><td>$896</td><td>$1,104</td><td>$985</td><td>$951</td><td>$7,863</td><td>$-</td></tr><tr><td>Operating leases</td><td>5,312</td><td>576</td><td>570</td><td>488</td><td>425</td><td>352</td><td>2,901</td><td>-</td></tr><tr><td>Capital lease obligations [b]</td><td>2,975</td><td>290</td><td>292</td><td>247</td><td>256</td><td>267</td><td>1,623</td><td>-</td></tr><tr><td>Purchase obligations [c]</td><td>2,738</td><td>386</td><td>317</td><td>242</td><td>249</td><td>228</td><td>1,284</td><td>32</td></tr><tr><td>Other post retirement benefits [d]</td><td>435</td><td>41</td><td>42</td><td>43</td><td>43</td><td>44</td><td>222</td><td>-</td></tr><tr><td>Income tax contingencies [e]</td><td>61</td><td>1</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>60</td></tr><tr><td>Total contractual obligations</td><td>$24,166</td><td>$2,140</td><td>$2,117</td><td>$2,124</td><td>$1,958</td><td>$1,842</td><td>$13,893</td><td>$92</td></tr></table>

Question: what was the percentage increase in the cash provided by operating activities from 2006 to 2007