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', '2015', '2014', '2013'], ['cash provided by operating activities', '$ 7344', '$ 7385', '$ 6823'], ['cash used in investing activities', '-4476 ( 4476 )', '-4249 ( 4249 )', '-3405 ( 3405 )'], ['dividends paid', '-2344 ( 2344 )', '-1632 ( 1632 )', '-1333 ( 1333 )'], ['free cash flow', '$ 524', '$ 1504', '$ 2085']]
2016 outlook f0b7 safety 2013 operating a safe railroad benefits all our constituents : our employees , customers , shareholders and the communities we serve .we will continue using a multi-faceted approach to safety , utilizing technology , risk assessment , quality control , training and employee engagement , and targeted capital investments .we will continue using and expanding the deployment of total safety culture and courage to care throughout our operations , which allows us to identify and implement best practices for employee and operational safety .we will continue our efforts to increase detection of rail defects ; improve or close crossings ; and educate the public and law enforcement agencies about crossing safety through a combination of our own programs ( including risk assessment strategies ) , industry programs and local community activities across our network .f0b7 network operations 2013 in 2016 , we will continue to align resources with customer demand , continue to improve network performance , and maintain our surge capability .f0b7 fuel prices 2013 with the dramatic drop in fuel prices during 2015 , fuel price projections continue to be uncertain in the current environment .we again could see volatile fuel prices during the year , as they are sensitive to global and u.s .domestic demand , refining capacity , geopolitical events , weather conditions and other factors .as prices fluctuate , there will be a timing impact on earnings , as our fuel surcharge programs trail fluctuations in fuel price by approximately two months .continuing lower fuel prices could have a positive impact on the economy by increasing consumer discretionary spending that potentially could increase demand for various consumer products that we transport .alternatively , lower fuel prices will likely have a negative impact on other commodities such as coal , frac sand and crude oil shipments .f0b7 capital plan 2013 in 2016 , we expect our capital plan to be approximately $ 3.75 billion , including expenditures for ptc , 230 locomotives and 450 freight cars .the capital plan may be revised if business conditions warrant or if new laws or regulations affect our ability to generate sufficient returns on these investments .( see further discussion in this item 7 under liquidity and capital resources 2013 capital plan. ) f0b7 financial expectations 2013 economic conditions in many of our market sectors continue to drive uncertainty with respect to our volume levels .we expect volumes to be down slightly in 2016 compared to 2015 , but will depend on the overall economy and market conditions .the strong u.s .dollar and historic low commodity prices could also drive continued volatility .one of the biggest uncertainties is the outlook for energy markets , which will bring both challenges and opportunities .in the current environment , we expect continued margin improvement driven by continued pricing opportunities , ongoing productivity initiatives , and the ability to leverage our resources and strengthen our franchise .over the longer term , we expect the overall u.s .economy to continue to improve at a modest pace , with some markets outperforming others. .

Question: what was the percentage change in free cash flow from 2013 to 2014?
Answer: -27%