Financial report context:
4 . stock options and other stock plans we have 100962 options outstanding under the 1993 stock option and retention stock plan of union pacific corporation ( 1993 plan ) . there are 7140 restricted shares outstanding under the 1992 restricted stock plan for non-employee directors of union pacific corporation . we no longer grant options or awards of retention shares and units under these plans . in april 2000 , the shareholders approved the union pacific corporation 2000 directors plan ( directors plan ) whereby 1100000 shares of our common stock were reserved for issuance to our non-employee directors . under the directors plan , each non-employee director , upon his or her initial election to the board of directors , receives a grant of 2000 shares of retention shares or retention stock units . prior to december 31 , 2007 , each non-employee director received annually an option to purchase at fair value a number of shares of our common stock , not to exceed 10000 shares during any calendar year , determined by dividing 60000 by 1/3 of the fair market value of one share of our common stock on the date of such board of directors meeting , with the resulting quotient rounded up or down to the nearest 50 shares . as of december 31 , 2009 , 18000 restricted shares were outstanding under the directors plan and 292000 options were outstanding under the directors plan . the union pacific corporation 2001 stock incentive plan ( 2001 plan ) was approved by the shareholders in april 2001 . the 2001 plan reserved 24000000 shares of our common stock for issuance to eligible employees of the corporation and its subsidiaries in the form of non-qualified options , incentive stock options , retention shares , stock units , and incentive bonus awards . non-employee directors were not eligible for awards under the 2001 plan . as of december 31 , 2009 , 3366230 options were outstanding under the 2001 plan . we no longer grant any stock options or other stock or unit awards under this plan . the union pacific corporation 2004 stock incentive plan ( 2004 plan ) was approved by shareholders in april 2004 . the 2004 plan reserved 42000000 shares of our common stock for issuance , plus any shares subject to awards made under the 2001 plan and the 1993 plan that were outstanding on april 16 , 2004 , and became available for regrant pursuant to the terms of the 2004 plan . under the 2004 plan , non- qualified options , stock appreciation rights , retention shares , stock units , and incentive bonus awards may be granted to eligible employees of the corporation and its subsidiaries . non-employee directors are not eligible for awards under the 2004 plan . as of december 31 , 2009 , 8939710 options and 3778997 retention shares and stock units were outstanding under the 2004 plan . pursuant to the above plans 33559150 ; 36961123 ; and 38601728 shares of our common stock were authorized and available for grant at december 31 , 2009 , 2008 , and 2007 , respectively . stock options 2013 we estimate the fair value of our stock option awards using the black-scholes option pricing model . groups of employees and non-employee directors that have similar historical and expected exercise behavior are considered separately for valuation purposes . the table below shows the annual weighted-average assumptions used for valuation purposes : weighted-average assumptions 2009 2008 2007 .

Financial table:
weighted-average assumptions: risk-free interest rate; 2009: 1.9% ( 1.9 % ); 2008: 2.8% ( 2.8 % ); 2007: 4.9% ( 4.9 % )
weighted-average assumptions: dividend yield; 2009: 2.3% ( 2.3 % ); 2008: 1.4% ( 1.4 % ); 2007: 1.4% ( 1.4 % )
weighted-average assumptions: expected life ( years ); 2009: 5.1; 2008: 5.3; 2007: 4.7
weighted-average assumptions: volatility; 2009: 31.3% ( 31.3 % ); 2008: 22.2% ( 22.2 % ); 2007: 20.9% ( 20.9 % )
weighted-average assumptions: weighted-average grant-date fair value of options granted; 2009: $ 11.33; 2008: $ 13.35; 2007: $ 11.19

Additional report context:
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Question: how many options were issued under the 2001 plan as of december 31 , 2009?
Answer: 20633770