reinsurance commissions , fees and other revenue increased 1% ( 1 % ) driven by a favorable foreign currency translation of 2% ( 2 % ) and was partially offset by a 1% ( 1 % ) decline in dispositions , net of acquisitions and other .organic revenue was flat primarily resulting from strong growth in the capital market transactions and advisory business , partially offset by declines in global facultative placements .operating income operating income increased $ 120 million , or 10% ( 10 % ) , from 2010 to $ 1.3 billion in 2011 .in 2011 , operating income margins in this segment were 19.3% ( 19.3 % ) , up 70 basis points from 18.6% ( 18.6 % ) in 2010 .operating margin improvement was primarily driven by revenue growth , reduced costs of restructuring initiatives and realization of the benefits of those restructuring plans , which was partially offset by the negative impact of expense increases related to investment in the business , lease termination costs , legacy receivables write-off , and foreign currency exchange rates .hr solutions .
[['years ended december 31,', '2011', '2010', '2009'], ['revenue', '$ 4501', '$ 2111', '$ 1267'], ['operating income', '448', '234', '203'], ['operating margin', '10.0% ( 10.0 % )', '11.1% ( 11.1 % )', '16.0% ( 16.0 % )']]
in october 2010 , we completed the acquisition of hewitt , one of the world 2019s leading human resource consulting and outsourcing companies .hewitt operates globally together with aon 2019s existing consulting and outsourcing operations under the newly created aon hewitt brand .hewitt 2019s operating results are included in aon 2019s results of operations beginning october 1 , 2010 .our hr solutions segment generated approximately 40% ( 40 % ) of our consolidated total revenues in 2011 and provides a broad range of human capital services , as follows : 2022 health and benefits advises clients about how to structure , fund , and administer employee benefit programs that attract , retain , and motivate employees .benefits consulting includes health and welfare , executive benefits , workforce strategies and productivity , absence management , benefits administration , data-driven health , compliance , employee commitment , investment advisory and elective benefits services .effective january 1 , 2012 , this line of business will be included in the results of the risk solutions segment .2022 retirement specializes in global actuarial services , defined contribution consulting , investment consulting , tax and erisa consulting , and pension administration .2022 compensation focuses on compensatory advisory/counsel including : compensation planning design , executive reward strategies , salary survey and benchmarking , market share studies and sales force effectiveness , with special expertise in the financial services and technology industries .2022 strategic human capital delivers advice to complex global organizations on talent , change and organizational effectiveness issues , including talent strategy and acquisition , executive on-boarding , performance management , leadership assessment and development , communication strategy , workforce training and change management .2022 benefits administration applies our hr expertise primarily through defined benefit ( pension ) , defined contribution ( 401 ( k ) ) , and health and welfare administrative services .our model replaces the resource-intensive processes once required to administer benefit plans with more efficient , effective , and less costly solutions .2022 human resource business processing outsourcing ( 2018 2018hr bpo 2019 2019 ) provides market-leading solutions to manage employee data ; administer benefits , payroll and other human resources processes ; and .

Question: what is the highest revenue observed in this period?
Answer: 4501
Explanation: it is the maximum value .