{"pre_text": ["results of operations year ended december 31 , 2006 compared to year ended december 31 , 2005 the historical results of operations of pca for the years ended december 31 , 2006 and 2005 are set forth below : for the year ended december 31 , ( in millions ) 2006 2005 change ."], "post_text": ["net sales net sales increased by $ 193.4 million , or 9.7% ( 9.7 % ) , for the year ended december 31 , 2006 from the year ended december 31 , 2005 .", "net sales increased primarily due to increased sales prices and volumes of corrugated products and containerboard compared to 2005 .", "total corrugated products volume sold increased 0.4% ( 0.4 % ) to 31.3 billion square feet in 2006 compared to 31.2 billion square feet in 2005 .", "on a comparable shipment-per-workday basis , corrugated products sales volume increased 0.8% ( 0.8 % ) in 2006 from 2005 .", "shipments-per-workday is calculated by dividing our total corrugated products volume during the year by the number of workdays within the year .", "the larger percentage increase on a shipment-per-workday basis was due to the fact that 2006 had one less workday ( 249 days ) , those days not falling on a weekend or holiday , than 2005 ( 250 days ) .", "containerboard sales volume to external domestic and export customers increased 15.6% ( 15.6 % ) to 482000 tons for the year ended december 31 , 2006 from 417000 tons in 2005 .", "income from operations income from operations increased by $ 109.8 million , or 94.6% ( 94.6 % ) , for the year ended december 31 , 2006 compared to 2005 .", "included in income from operations for the year ended december 31 , 2005 is income of $ 14.0 million , net of expenses , consisting of two dividends paid to pca by southern timber venture , llc ( stv ) , the timberlands joint venture in which pca owns a 311 20443% ( 20443 % ) ownership interest .", "excluding the dividends from stv , income from operations increased $ 123.8 million in 2006 compared to 2005 .", "the $ 123.8 million increase in income from operations was primarily attributable to higher sales prices and volume as well as improved mix of business ( $ 195.6 million ) , partially offset by increased costs related to transportation ( $ 18.9 million ) , energy , primarily purchased fuels and electricity ( $ 18.3 million ) , wage increases for hourly and salaried personnel ( $ 16.9 million ) , medical , pension and other benefit costs ( $ 9.9 million ) , and incentive compensation ( $ 6.5 million ) .", "gross profit increased $ 137.1 million , or 44.7% ( 44.7 % ) , for the year ended december 31 , 2006 from the year ended december 31 , 2005 .", "gross profit as a percentage of net sales increased from 15.4% ( 15.4 % ) of net sales in 2005 to 20.3% ( 20.3 % ) of net sales in the current year primarily due to the increased sales prices described previously .", "selling and administrative expenses increased $ 12.3 million , or 8.4% ( 8.4 % ) , for the year ended december 31 , 2006 from the comparable period in 2005 .", "the increase was primarily the result of increased salary and ."], "table": [["( in millions )", "for the year ended december 31 , 2006", "for the year ended december 31 , 2005", "change"], ["net sales", "$ 2187.1", "$ 1993.7", "$ 193.4"], ["income from operations", "$ 225.9", "$ 116.1", "$ 109.8"], ["interest expense net", "-31.2 ( 31.2 )", "-28.1 ( 28.1 )", "-3.1 ( 3.1 )"], ["income before taxes", "194.7", "88.0", "106.7"], ["provision for income taxes", "-69.7 ( 69.7 )", "-35.4 ( 35.4 )", "-34.3 ( 34.3 )"], ["net income", "$ 125.0", "$ 52.6", "$ 72.4"]], "table_ori": [["", "For the Year Ended December 31,", ""], ["<i>(In millions)</i>", "2006", "2005", "Change"], ["Net sales", "$2,187.1", "$1,993.7", "$193.4"], ["Income from operations", "$225.9", "$116.1", "$109.8"], ["Interest expense, net", "(31.2)", "(28.1)", "(3.1)"], ["Income before taxes", "194.7", "88.0", "106.7"], ["Provision for income taxes", "(69.7)", "(35.4)", "(34.3)"], ["Net income", "$125.0", "$52.6", "$72.4"]]}

Question: total corrugated products volume sold increased by how many billion square feet in 2006 compared to 2005?
Evidence:
text_3: total corrugated products volume sold increased 0.4% ( 0.4 % ) to 31.3 billion square feet in 2006 compared to 31.2 billion square feet in 2005 .
Program: subtract(31.3, 31.2)
Answer:
str_answer: 0.1
exe_answer: 0.1