Read the following texts and table with financial data from an S&P 500 earnings report carefully.Based on the question-answer history (if provided), answer the last question. The answer may require mathematical calculation based on the data provided.


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 . <table class='wikitable'><tr><td>1</td><td>in millions of dollars</td><td>2018</td><td>2017</td><td>2016</td></tr><tr><td>2</td><td>charges for estimated awards to retirement-eligible employees</td><td>$ 669</td><td>$ 659</td><td>$ 555</td></tr><tr><td>3</td><td>amortization of deferred cash awards deferred cash stock units and performance stock units</td><td>202</td><td>354</td><td>336</td></tr><tr><td>4</td><td>immediately vested stock award expense ( 1 )</td><td>75</td><td>70</td><td>73</td></tr><tr><td>5</td><td>amortization of restricted and deferred stock awards ( 2 )</td><td>435</td><td>474</td><td>509</td></tr><tr><td>6</td><td>other variable incentive compensation</td><td>640</td><td>694</td><td>710</td></tr><tr><td>7</td><td>total</td><td>$ 2021</td><td>$ 2251</td><td>$ 2183</td></tr></table> ( 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 is the difference in total incentive compensation from 2017 to 2018?

-230.0