pre_text: the following table provides the weighted average assumptions used in the black-scholes option-pricing model for grants and the resulting weighted average grant date fair value per share of stock options granted for the years ended december 31: .
post_text: stock units during 2018 , 2017 and 2016 , the company granted rsus to certain employees under the 2007 plan and 2017 omnibus plan , as applicable . rsus generally vest based on continued employment with the company over periods ranging from one to three years. .
table: 2018 2017 2016
table: Intrinsic value $9 $10 $18
table: Exercise proceeds 7 11 15
table: Income tax benefit realized 2 3 6
question: Analyse this data from a financial earnings document. by how much did the intrinsic value decrease from 2016 to 2018?