levels during 2008 , an indication that efforts to improve network operations translated into better customer service .2022 fuel prices 2013 crude oil prices increased at a steady rate through the first seven months of 2008 , closing at a record high of $ 145.29 a barrel in early july .as the economy worsened during the third and fourth quarters , fuel prices dropped dramatically , hitting $ 33.87 per barrel in december , a near five-year low .despite these price declines toward the end of the year , our 2008 average fuel price increased by 39% ( 39 % ) and added $ 1.1 billion of operating expenses compared to 2007 .our fuel surcharge programs helped offset the impact of higher fuel prices .in addition , we reduced our consumption rate by 4% ( 4 % ) , saving approximately 58 million gallons of fuel during the year .the use of newer , more fuel efficient locomotives ; our fuel conservation programs ; improved network operations ; and a shift in commodity mix , primarily due to growth in bulk shipments , contributed to the improvement .2022 free cash flow 2013 cash generated by operating activities totaled a record $ 4.1 billion , yielding free cash flow of $ 825 million in 2008 .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 ) : millions of dollars 2008 2007 2006 .
[['millions of dollars', '2008', '2007', '2006'], ['cash provided by operating activities', '$ 4070', '$ 3277', '$ 2880'], ['cash used in investing activities', '-2764 ( 2764 )', '-2426 ( 2426 )', '-2042 ( 2042 )'], ['dividends paid', '-481 ( 481 )', '-364 ( 364 )', '-322 ( 322 )'], ['free cash flow', '$ 825', '$ 487', '$ 516']]
2009 outlook 2022 safety 2013 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 and engaging our employees .we plan to continue implementation of 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 railroad and industry programs , along with other activities .2022 transportation plan 2013 in 2009 , 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 , and improve productivity using industrial engineering techniques .2022 fuel prices 2013 on average , we expect fuel prices to decrease substantially from the average price we paid in 2008 .however , due to economic uncertainty , other global pressures , and weather incidents , fuel prices again could be volatile during the year .to reduce the impact of fuel price on earnings , we .

Question: what was the percentage change in free cash flow from 2006 to 2007?
Answer: -6%