estimated future pension benefit payments for the next ten years under the plan ( in millions ) are as follows : estimated future payments: .
what was the percent of the estimated future pension benefit payments increase from 2011 to 2012
bfi post retirement healthcare plan we acquired obligations under the bfi post retirement healthcare plan as part of our acquisition of allied . this plan provides continued medical coverage for certain former employees following their retirement , including some employees subject to collective bargaining agreements . eligibility for this plan is limited to certain of those employees who had ten or more years of service and were age 55 or older as of december 31 , 1998 , and certain employees in california who were hired on or before december 31 , 2005 and who retire on or after age 55 with at least thirty years of service . liabilities acquired for this plan were $ 1.2 million and $ 1.3 million , respectively , at the acquisition date and at december 31 , 2008 . multi-employer pension plans we contribute to 25 multi-employer pension plans under collective bargaining agreements covering union- represented employees . we acquired responsibility for contributions for a portion of these plans as part of our acquisition of allied . approximately 22% ( 22 % ) of our total current employees are participants in such multi- employer plans . these plans generally provide retirement benefits to participants based on their service to contributing employers . we do not administer these multi-employer plans . in general , these plans are managed by a board of trustees with the unions appointing certain trustees and other contributing employers of the plan appointing certain members . we generally are not represented on the board of trustees . we do not have current plan financial information from the plans 2019 administrators , but based on the information available to us , it is possible that some of the multi-employer plans to which we contribute may be underfunded . the pension protection act , enacted in august 2006 , requires underfunded pension plans to improve their funding ratios within prescribed intervals based on the level of their underfunding . until the plan trustees develop the funding improvement plans or rehabilitation plans as required by the pension protection act , we are unable to determine the amount of assessments we may be subject to , if any . accordingly , we cannot determine at this time the impact that the pension protection act may have on our consolidated financial position , results of operations or cash flows . furthermore , under current law regarding multi-employer benefit plans , a plan 2019s termination , our voluntary withdrawal , or the mass withdrawal of all contributing employers from any under-funded , multi-employer pension plan would require us to make payments to the plan for our proportionate share of the multi- employer plan 2019s unfunded vested liabilities . it is possible that there may be a mass withdrawal of employers contributing to these plans or plans may terminate in the near future . we could have adjustments to our estimates for these matters in the near term that could have a material effect on our consolidated financial condition , results of operations or cash flows . our pension expense for multi-employer plans was $ 21.8 million , $ 18.9 million and $ 17.3 million for the years ended december 31 , 2008 , 2007 and 2006 , respectively . republic services , inc . and subsidiaries notes to consolidated financial statements %%transmsg*** transmitting job : p14076 pcn : 133000000 ***%%pcmsg|131 |00027|yes|no|02/28/2009 21:12|0|0|page is valid , no graphics -- color : d| .