shutdown . the customer , which primarily received products from the tonnage gases segment , filed for bankruptcy in may 2012 and announced the mill shutdown in august 2012 . pension settlement loss our u.s . supplemental pension plan provides for a lump sum benefit payment option at the time of retirement , or for corporate officers , six months after the retirement date . pension settlements are recognized when cash payments exceed the sum of the service and interest cost components of net periodic pension cost of the plan for the fiscal year . the participant 2019s vested benefit is considered fully settled upon cash payment of the lump sum . we recognized $ 12.4 of settlement charges in 2013 . advisory costs during the fourth quarter of 2013 , we incurred legal and other advisory fees of $ 10.1 ( $ 6.4 after-tax , or $ .03 per share ) in connection with our response to the rapid acquisition of a large position in shares of our common stock by pershing square capital management llc and its affiliates ( pershing square ) . these fees , which are reflected on the consolidated income statements as 201cadvisory costs , 201d include costs incurred before and after pershing square 2019s disclosure of its holdings and cover advisory services related to the adoption of the shareholders rights plan , preparation for a potential proxy solicitation campaign , and entering into an agreement with pershing square . other income ( expense ) , net items recorded to other income ( expense ) , net arise from transactions and events not directly related to our principal income earning activities . the detail of other income ( expense ) , net is presented in note 23 , supplemental information , to the consolidated financial statements . 2013 vs . 2012 other income ( expense ) , net of $ 70.2 increased $ 23.1 , primarily due to higher gains from the sale of a number of small assets and investments and a favorable commercial contract settlement , partially offset by lower government grants . otherwise , no individual items were significant in comparison to the prior year . 2012 vs . 2011 other income ( expense ) , net of $ 47.1 increased $ 5.4 , primarily due to favorable foreign exchange and reimbursements from government grants for expense , partially offset by lower gains from the sale of assets . otherwise , no individual items were significant in comparison to the prior year . interest expense .

Table: 2013 2012 2011 interest incurred $ 167.6 $ 153.9 $ 138.2 less : capitalized interest 25.8 30.2 22.7 interest expense $ 141.8 $ 123.7 $ 115.5

2013 vs . 2012 interest incurred increased $ 13.7 . the increase was driven primarily by a higher average debt balance for $ 41 , partially offset by a lower average interest rate on the debt portfolio of $ 24 . the change in capitalized interest was driven by a decrease in project spending and a lower average interest rate . 2012 vs . 2011 interest incurred increased $ 15.7 . the increase was driven primarily by a higher average debt balance and debt issuance costs related to the indura s.a . acquisition , partially offset by the impact of a stronger dollar on the translation of foreign currency interest . the change in capitalized interest was driven by an increase in project spending which qualified for capitalization . effective tax rate the effective tax rate equals the income tax provision divided by income from continuing operations before taxes . refer to note 22 , income taxes , to the consolidated financial statements for details on factors affecting the effective tax rate . 2013 vs . 2012 on a gaap basis , the effective tax rate was 22.8% ( 22.8 % ) and 21.9% ( 21.9 % ) in 2013 and 2012 , respectively . the current year rate includes income tax benefits of $ 73.7 related to the business restructuring and cost reduction plans and $ 3.7 for the advisory costs . the prior year rate includes income tax benefits of $ 105.0 related to the business restructuring and cost reduction plans , $ 58.3 related to the second quarter spanish tax ruling , and $ 3.7 related to the customer .

Question: considering the gaap basis , what was the growth observed in the effective tax rate during 2012 and 2013?
Answer: 0.9%
Calculation: subtract(22.8%, 21.9%)
Explanation: it is the variation between these effective tax rates during 2012 and 2013 .