the principal components of eog's rollforward of valuation allowances for deferred tax assets were as follows ( in thousands ) : .
what is the lowest beginning balance observed during 2014-2016?
( 1 ) increase in valuation allowance related to the generation of tax net operating losses and other deferred tax assets . ( 2 ) decrease in valuation allowance associated with adjustments to certain deferred tax assets and their related allowance . ( 3 ) represents dispositions/revisions/foreign exchange rate variances and the effect of statutory income tax rate changes . the balance of unrecognized tax benefits at december 31 , 2016 , was $ 36 million , of which $ 2 million may potentially have an earnings impact . eog records interest and penalties related to unrecognized tax benefits to its income tax provision . currently , $ 2 million of interest has been recognized in the consolidated statements of income and comprehensive income . eog does not anticipate that the amount of the unrecognized tax benefits will significantly change during the next twelve months . eog and its subsidiaries file income tax returns and are subject to tax audits in the united states and various state , local and foreign jurisdictions . eog's earliest open tax years in its principal jurisdictions are as follows : united states federal ( 2011 ) , canada ( 2012 ) , united kingdom ( 2015 ) , trinidad ( 2010 ) and china ( 2008 ) . eog's foreign subsidiaries' undistributed earnings of approximately $ 2 billion at december 31 , 2016 , are no longer considered to be permanently reinvested outside the united states and , accordingly , eog has cumulatively recorded $ 280 million of united states federal , foreign and state deferred income taxes . eog changed its permanent reinvestment assertion in 2014 . in 2016 , eog's alternative minimum tax ( amt ) credits were reduced by $ 21 million mostly as a result of carry-back claims and certain elections . remaining amt credits of $ 758 million , resulting from amt paid in prior years , will be carried forward indefinitely until they are used to offset regular income taxes in future periods . the ability of eog to utilize these amt credit carryforwards to reduce federal income taxes may become subject to various limitations under the internal revenue code . such limitations may arise if certain ownership changes ( as defined for income tax purposes ) were to occur . as of december 31 , 2016 , eog had state income tax net operating losses ( nols ) being carried forward of approximately $ 1.6 billion , which , if unused , expire between 2017 and 2035 . during 2016 , eog's united kingdom subsidiary incurred a tax nol of approximately $ 38 million which , along with prior years' nols of $ 740 million , will be carried forward indefinitely . as described above , these nols have been evaluated for the likelihood of future utilization , and valuation allowances have been established for the portion of these deferred tax assets that do not meet the "more likely than not" threshold . 7 . employee benefit plans stock-based compensation during 2016 , eog maintained various stock-based compensation plans as discussed below . eog recognizes compensation expense on grants of stock options , sars , restricted stock and restricted stock units , performance units and performance stock , and grants made under the eog resources , inc . employee stock purchase plan ( espp ) . stock-based compensation expense is calculated based upon the grant date estimated fair value of the awards , net of forfeitures , based upon eog's historical employee turnover rate . compensation expense is amortized over the shorter of the vesting period or the period from date of grant until the date the employee becomes eligible to retire without company approval. .