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humana inc . notes to consolidated financial statements 2014 ( continued ) amortization expense for other intangible assets was approximately $ 75 million in 2017 , $ 77 million in 2016 , and $ 93 million in 2015 . the following table presents our estimate of amortization expense for each of the five next succeeding fiscal years: .
what was the percent of the decline in amortization expense for other intangible assets from 2016 to 2017
notes to consolidated financial statements 2014 ( continued ) amortization expense for other intangible assets was approximately $ 75 million in 2017 , $ 77 million in 2016 , and $ 93 million in 2015 .
( in millions )
for the years ending december 31,
2018 $ 64
2019 54
2020 52
2021 19
2022 16