2016 compared with 2015 net gains on investments of $ 57 million in 2016 decreased $ 52 million from 2015 due to lower net gains in 2016 . net gains on investments in 2015 included a $ 40 million gain related to the bkca acquisition and a $ 35 million unrealized gain on a private equity investment . interest and dividend income increased $ 14 million from 2015 primarily due to higher dividend income in 2016 . 2015 compared with 2014 net gains on investments of $ 109 million in 2015 decreased $ 45 million from 2014 due to lower net gains in 2015 . net gains on investments in 2015 included a $ 40 million gain related to the bkca acquisition and a $ 35 million unrealized gain on a private equity investment . net gains on investments in 2014 included the positive impact of the monetization of a nonstrategic , opportunistic private equity investment . interest expense decreased $ 28 million from 2014 primarily due to repayments of long-term borrowings in the fourth quarter of 2014 . income tax expense .

gaap 2016 (1): operating income ( 1 ): 4570
total nonoperating income ( expense ) ( 1 ) ( 2 ): -108
income before income taxes ( 2 ): 4462
income tax expense: 1290
effective tax rate: -28.9
gaap 2015 (1): operating income ( 1 ): 4664
total nonoperating income ( expense ) ( 1 ) ( 2 ): -69
income before income taxes ( 2 ): 4595
income tax expense: 1250
effective tax rate: -27.2
gaap 2014: operating income ( 1 ): 4474
total nonoperating income ( expense ) ( 1 ) ( 2 ): -49
income before income taxes ( 2 ): 4425
income tax expense: 1131
effective tax rate: -25.6
gaap 2016 (2): operating income ( 1 ): 4674
total nonoperating income ( expense ) ( 1 ) ( 2 ): -108
income before income taxes ( 2 ): 4566
income tax expense: 1352
effective tax rate: -29.6
gaap 2015 (2): operating income ( 1 ): 4695
total nonoperating income ( expense ) ( 1 ) ( 2 ): -70
income before income taxes ( 2 ): 4625
income tax expense: 1312
effective tax rate: -28.4
2014: operating income ( 1 ): 4563
total nonoperating income ( expense ) ( 1 ) ( 2 ): -56
income before income taxes ( 2 ): 4507
income tax expense: 1197
effective tax rate: -26.6

( 1 ) see non-gaap financial measures for further information on and reconciliation of as adjusted items . ( 2 ) net of net income ( loss ) attributable to nci . the company 2019s tax rate is affected by tax rates in foreign jurisdictions and the relative amount of income earned in those jurisdictions , which the company expects to be fairly consistent in the near term . the significant foreign jurisdictions that have lower statutory tax rates than the u.s . federal statutory rate of 35% ( 35 % ) include the united kingdom , channel islands , ireland and canada . u.s . income taxes were not provided for certain undistributed foreign earnings intended to be indefinitely reinvested outside the united states . 2016 . income tax expense ( gaap ) reflected : 2022 a net noncash benefit of $ 30 million , primarily associated with the revaluation of certain deferred income tax liabilities ; and 2022 a benefit from $ 65 million of nonrecurring items , including the resolution of certain outstanding tax matters . the as adjusted effective tax rate of 29.6% ( 29.6 % ) for 2016 excluded the net noncash benefit of $ 30 million mentioned above , as it will not have a cash flow impact and to ensure comparability among periods presented . 2015 . income tax expense ( gaap ) reflected : 2022 a net noncash benefit of $ 54 million , primarily associated with the revaluation of certain deferred income tax liabilities ; and 2022 a benefit from $ 75 million of nonrecurring items , primarily due to the realization of losses from changes in the company 2019s organizational tax structure and the resolution of certain outstanding tax matters . the as adjusted effective tax rate of 28.4% ( 28.4 % ) for 2015 excluded the net noncash benefit of $ 54 million mentioned above , as it will not have a cash flow impact and to ensure comparability among periods presented . 2014 . income tax expense ( gaap ) reflected : 2022 a $ 94 million tax benefit , primarily due to the resolution of certain outstanding tax matters related to the acquisition of bgi , including the previously mentioned $ 50 million tax benefit ( see executive summary for more information ) ; 2022 a $ 73 million net tax benefit related to several favorable nonrecurring items ; and 2022 a net noncash benefit of $ 9 million associated with the revaluation of deferred income tax liabilities . the as adjusted effective tax rate of 26.6% ( 26.6 % ) for 2014 excluded the $ 9 million net noncash benefit as it will not have a cash flow impact and to ensure comparability among periods presented and the $ 50 million tax benefit mentioned above . the $ 50 million general and administrative expense and $ 50 million tax benefit have been excluded from as adjusted results as there is no impact on blackrock 2019s book value . balance sheet overview as adjusted balance sheet the following table presents a reconciliation of the consolidated statement of financial condition presented on a gaap basis to the consolidated statement of financial condition , excluding the impact of separate account assets and separate account collateral held under securities lending agreements ( directly related to lending separate account securities ) and separate account liabilities and separate account collateral liabilities under securities lending agreements and consolidated sponsored investment funds , including consolidated vies . the company presents the as adjusted balance sheet as additional information to enable investors to exclude certain .

Questions:
what was the effective tax rate in 2016?
and what was it in 2015?
what was, then, the change over the year?
and in the last year of that period, what was the operating income?
and what was the income tax expense?
what was, then, the net income for that year?

Answers:
28.9%
27.2%
1.7%
4570
1290
3280