valuation techniques 2013 cash equivalents are mostly comprised of short-term money-market instruments and are valued at cost , which approximates fair value .
u.s .
equity securities and international equity securities categorized as level 1 are traded on active national and international exchanges and are valued at their closing prices on the last trading day of the year .
for u.s .
equity securities and international equity securities not traded on an active exchange , or if the closing price is not available , the trustee obtains indicative quotes from a pricing vendor , broker or investment manager .
these securities are categorized as level 2 if the custodian obtains corroborated quotes from a pricing vendor or categorized as level 3 if the custodian obtains uncorroborated quotes from a broker or investment manager .
commingled equity funds categorized as level 1 are traded on active national and international exchanges and are valued at their closing prices on the last trading day of the year .
for commingled equity funds not traded on an active exchange , or if the closing price is not available , the trustee obtains indicative quotes from a pricing vendor , broker or investment manager .
these securities are categorized as level 2 if the custodian obtains corroborated quotes from a pricing vendor .
fixed income investments categorized as level 2 are valued by the trustee using pricing models that use verifiable observable market data ( e.g. , interest rates and yield curves observable at commonly quoted intervals and credit spreads ) , bids provided by brokers or dealers or quoted prices of securities with similar characteristics .
fixed income investments are categorized as level 3 when valuations using observable inputs are unavailable .
the trustee typically obtains pricing based on indicative quotes or bid evaluations from vendors , brokers or the investment manager .
in addition , certain other fixed income investments categorized as level 3 are valued using a discounted cash flow approach .
significant inputs include projected annuity payments and the discount rate applied to those payments .
certain commingled equity funds , consisting of equity mutual funds , are valued using the nav .
the nav valuations are based on the underlying investments and typically redeemable within 90 days .
private equity funds consist of partnership and co-investment funds .
the nav is based on valuation models of the underlying securities , which includes unobservable inputs that cannot be corroborated using verifiable observable market data .
these funds typically have redemption periods between eight and 12 years .
real estate funds consist of partnerships , most of which are closed-end funds , for which the nav is based on valuation models and periodic appraisals .
these funds typically have redemption periods between eight and 10 years .
hedge funds consist of direct hedge funds for which the nav is generally based on the valuation of the underlying investments .
redemptions in hedge funds are based on the specific terms of each fund , and generally range from a minimum of one month to several months .
contributions and expected benefit payments the funding of our qualified defined benefit pension plans is determined in accordance with erisa , as amended by the ppa , and in a manner consistent with cas and internal revenue code rules .
we made contributions of $ 5.0 billion to our qualified defined benefit pension plans in 2018 , including required and discretionary contributions .
as a result of these contributions , we do not expect to make contributions to our qualified defined benefit pension plans in 2019 .
the following table presents estimated future benefit payments , which reflect expected future employee service , as of december 31 , 2018 ( in millions ) : .

2019
2020
2021
2022
2023
2024 – 2028
Qualified defined benefit pension plans
$2,350
$2,390
$2,470
$2,550
$2,610
$13,670
Retiree medical and life insurance plans
170
180
180
180
170
810

defined contribution plans we maintain a number of defined contribution plans , most with 401 ( k ) features , that cover substantially all of our employees .
under the provisions of our 401 ( k ) plans , we match most employees 2019 eligible contributions at rates specified in the plan documents .
our contributions were $ 658 million in 2018 , $ 613 million in 2017 and $ 617 million in 2016 , the majority of which were funded using our common stock .
our defined contribution plans held approximately 33.3 million and 35.5 million shares of our common stock as of december 31 , 2018 and 2017. .

Question: Analyse this data from a financial earnings document. what is the percentage change in 401 ( k ) contributions from 2016 to 2017?
Choices:
-0.12012
0.98541
-0.00494
-0.00648
616.99352
Correct choice index: 3