Please answer the given financial question based on the context.
Context: incentive compensation cost the following table shows components of compensation expense , relating to certain of the incentive compensation programs described above : in a0millions a0of a0dollars 2018 2017 2016 charges for estimated awards to retirement-eligible employees $ 669 $ 659 $ 555 amortization of deferred cash awards , deferred cash stock units and performance stock units 202 354 336 immediately vested stock award expense ( 1 ) 75 70 73 amortization of restricted and deferred stock awards ( 2 ) 435 474 509 .
|in millions of dollars|2018|2017|2016|
|charges for estimated awards to retirement-eligible employees|$ 669|$ 659|$ 555|
|amortization of deferred cash awards deferred cash stock units and performance stock units|202|354|336|
|immediately vested stock award expense ( 1 )|75|70|73|
|amortization of restricted and deferred stock awards ( 2 )|435|474|509|
|other variable incentive compensation|640|694|710|
|total|$ 2021|$ 2251|$ 2183|
( 1 ) represents expense for immediately vested stock awards that generally were stock payments in lieu of cash compensation . the expense is generally accrued as cash incentive compensation in the year prior to grant . ( 2 ) all periods include amortization expense for all unvested awards to non-retirement-eligible employees. .
Question: what percentage of total compensation expense in 2018 is composed of other variable incentive compensation?


Answer: The answer is:0.31667