2022 selling costs increased $ 5.4 million to $ 17.1 million in 2005 from $ 11.7 million in 2004 . this increase was due to increased headcount in our sales force and startup costs associated with our international growth initiatives . as a percentage of net revenues , selling costs increased to 6.1% ( 6.1 % ) in 2005 from 5.7% ( 5.7 % ) in 2004 due to the increased costs described above . 2022 payroll and related costs ( excluding those specifically related to marketing and selling ) increased $ 8.6 million to $ 26.9 million in 2005 , from $ 18.3 million in 2004 . the increase during 2005 was due to the following initiatives : we began to build our team to design and source our footwear line , which we expect to offer for the fall 2006 season , we added personnel to our information technology team to support our company-wide initiative to upgrade our information systems , we incurred equity compensation costs , we added personnel to operate our 3 new retail outlet stores , and we invested in the personnel needed to enhance our compliance function and operate as a public company . as a percentage of net revenues , payroll and related costs ( excluding those specifically related to marketing and selling ) increased to 9.6% ( 9.6 % ) in 2005 from 8.9% ( 8.9 % ) in 2004 due to the items described above . 2022 other corporate costs increased $ 7.2 million to $ 25.5 million in 2005 , from $ 18.3 million in 2004 . this increase was attributable to higher costs in support of our footwear initiative , freight and duty related to increased canada sales , expansion of our leased corporate office space and distribution facility , and necessary costs associated with being a public company . as a percentage of net revenues , other corporate costs were 9.1% ( 9.1 % ) in 2005 , which is a slight increase from 8.9% ( 8.9 % ) in 2004 due to the items noted above . income from operations increased $ 10.5 million , or 41.4% ( 41.4 % ) , to $ 35.9 million in 2005 from $ 25.4 million in 2004 . income from operations as a percentage of net revenues increased to 12.7% ( 12.7 % ) in 2005 from 12.4% ( 12.4 % ) in 2004 . this increase was a result of an increase in gross margin partially offset by an increase in selling , general and administrative expenses as a percentage of net revenues . interest expense , net increased $ 1.6 million to $ 2.9 million in 2005 from $ 1.3 million in 2004 . this increase was primarily due to higher average borrowings and a higher effective interest rate under our revolving credit facility prior to being repaid in november 2005 with proceeds from the initial public offering . provision for income taxes increased $ 5.5 million to $ 13.3 million in 2005 from $ 7.8 million in 2004 . for the year ended december 31 , 2005 our effective tax rate was 40.2% ( 40.2 % ) compared to 32.3% ( 32.3 % ) in 2004 . this increase was primarily due to an increase in our effective state tax rate , which reflected reduced state tax credits earned as a percentage of income before taxes . net income increased $ 3.4 million to $ 19.7 million in 2005 from $ 16.3 million in 2004 , as a result of the factors described above . year ended december 31 , 2004 compared to year ended december 31 , 2003 net revenues increased $ 89.8 million , or 77.8% ( 77.8 % ) , to $ 205.2 million in 2004 from $ 115.4 million in 2003 . the increase was a result of increases in both our net sales and license revenues as noted in the product category table below. .
what was the percent of the increase in interest expense from 2004 to 2005
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