approximately 710 asphalt-paving contractors , government entities ( states , counties , cities and townships ) and asphalt roofing shingle manufacturers . we also produce asphalt cements , polymerized asphalt , asphalt emulsions and industrial asphalts . retail marketing ssa , our wholly-owned subsidiary , sells gasoline and merchandise through owned and operated retail outlets primarily under the speedway ae and superamerica ae brands . diesel fuel is also sold at a number of these outlets . ssa retail outlets offer a wide variety of merchandise , such as prepared foods , beverages , and non-food items , as well as a significant number of proprietary items . as of december 31 , 2008 , ssa had 1617 retail outlets in nine states . sales of refined products through these retail outlets accounted for 15 percent of our refined product sales volumes in 2008 . revenues from sales of non-petroleum merchandise through these retail outlets totaled $ 2838 million in 2008 , $ 2796 million in 2007 and $ 2706 million in 2006 . the demand for gasoline is seasonal in a majority of ssa markets , usually with the highest demand during the summer driving season . profit levels from the sale of merchandise and services tend to be less volatile than profit levels from the retail sale of gasoline and diesel fuel . in october 2008 , we sold our interest in pilot travel centers llc ( 201cptc 201d ) , an operator of travel centers in the united states . pipeline transportation we own a system of pipelines through marathon pipe line llc ( 201cmpl 201d ) and ohio river pipe line llc ( 201corpl 201d ) , our wholly-owned subsidiaries . our pipeline systems transport crude oil and refined products primarily in the midwest and gulf coast regions to our refineries , our terminals and other pipeline systems . our mpl and orpl wholly-owned and undivided interest common carrier systems consist of 1815 miles of crude oil lines and 1826 miles of refined product lines comprising 34 systems located in 11 states . the mpl common carrier pipeline network is one of the largest petroleum pipeline systems in the united states , based on total barrels delivered . our common carrier pipeline systems are subject to state and federal energy regulatory commission regulations and guidelines , including published tariffs for the transportation of crude oil and refined products . third parties generated 11 percent of the crude oil and refined product shipments on our mpl and orpl common carrier pipelines in 2008 . our mpl and orpl common carrier pipelines transported the volumes shown in the following table for each of the last three years . pipeline barrels handled ( thousands of barrels per day ) 2008 2007 2006 .
what percentage of pipeline barrels handled consisted of crude oil trunk lines in 2007?
we also own 176 miles of private crude oil pipelines and 850 miles of private refined products pipelines , and we lease 217 miles of common carrier refined product pipelines . we have partial ownership interests in several pipeline companies that have approximately 780 miles of crude oil pipelines and 3000 miles of refined products pipelines , including about 800 miles operated by mpl . in addition , mpl operates most of our private pipelines and 985 miles of crude oil and 160 miles of natural gas pipelines owned by our e&p segment . our major refined product lines include the cardinal products pipeline and the wabash pipeline . the cardinal products pipeline delivers refined products from kenova , west virginia , to columbus , ohio . the wabash pipeline system delivers product from robinson , illinois , to various terminals in the area of chicago , illinois . other significant refined product pipelines owned and operated by mpl extend from : robinson , illinois , to louisville , kentucky ; garyville , louisiana , to zachary , louisiana ; and texas city , texas , to pasadena , texas. .