divestiture of our arrow and moores businesses , and an unfavorable sales mix of international plumbing products , which , in aggregate , decreased sales by two percent . net sales for 2016 were positively affected by increased sales volume of plumbing products , paints and other coating products and builders' hardware . net sales for 2016 were also positively affected by favorable sales mix of cabinets and windows , and net selling price increases of north american windows and north american and international plumbing products . net sales for 2016 were negatively affected by lower sales volume of cabinets and lower net selling prices of paints and other coating products . our gross profit margins were 32.2 percent , 34.2 percent and 33.4 percent in 2018 , 2017 and 2016 , respectively . the 2018 gross profit margin was negatively impacted by an increase in commodity costs , the recognition of the inventory step up adjustment established as a part of the the acquisition of kichler , an increase in other expenses ( such as logistics costs and salaries ) and unfavorable sales mix . these negative impacts were partially offset by an increase in net selling prices , the benefits associated with cost savings initiatives , and increased sales volume . the 2017 gross profit margin was positively impacted by increased sales volume , a more favorable relationship between net selling prices and commodity costs , and cost savings initiatives . selling , general and administrative expenses as a percent of sales were 17.7 percent in 2018 compared with 18.6 percent in 2017 and 18.7 percent in 2016 . the decrease in selling , general and administrative expenses , as a percentage of sales , was driven by leverage of fixed expenses , due primarily to increased sales volume , and improved cost control . the following table reconciles reported operating profit to operating profit , as adjusted to exclude certain items , dollars in millions: .

2018: operating profit as reported: 1211
rationalization charges: 14
kichler inventory step up adjustment: 40
operating profit as adjusted: 1265
operating profit margins as reported: -14.5
operating profit margins as adjusted: -15.1
2017: operating profit as reported: 1194
rationalization charges: 4
kichler inventory step up adjustment: 2014
operating profit as adjusted: 1198
operating profit margins as reported: -15.6
operating profit margins as adjusted: -15.7
2016: operating profit as reported: 1087
rationalization charges: 22
kichler inventory step up adjustment: 2014
operating profit as adjusted: 1109
operating profit margins as reported: -14.8
operating profit margins as adjusted: -15.1

operating profit margin in 2018 was negatively affected by an increase in commodity costs , the recognition of the inventory step up adjustment established as a part of the the acquisition of kichler and an increase in other expenses ( such as logistics costs , salaries and erp costs ) . these negative impacts were partially offset by increased net selling prices , benefits associated with cost savings initiatives and increased sales volume . operating profit margin in 2017 was positively impacted by increased sales volume , cost savings initiatives , and a more favorable relationship between net selling prices and commodity costs . operating profit margin in 2017 was negatively impacted by an increase in strategic growth investments and certain other expenses , including stock-based compensation , health insurance costs , trade show costs and increased head count . due to the recently-announced increase in tariffs on imported materials from china , and assuming tariffs rise to 25 percent in 2019 , we could be exposed to approximately $ 150 million of potential annual direct cost increases . we will work to mitigate the impact of these tariffs through a combination of price increases , supplier negotiations , supply chain repositioning and other internal productivity measures . other income ( expense ) , net other , net , for 2018 included $ 14 million of net periodic pension and post-retirement benefit cost and $ 8 million of realized foreign currency losses . these expenses were partially offset by $ 3 million of earnings related to equity method investments and $ 1 million related to distributions from private equity funds . other , net , for 2017 included $ 26 million related to periodic pension and post-retirement benefit costs , $ 13 million net loss related to the divestitures of moores and arrow and $ 2 million related to the impairment of a private equity fund , partially offset by $ 3 million related to distributions from private equity funds and $ 1 million of earnings related to equity method investments. .

Questions:
what was the operating profit margin as adjusted in 2017?
and what was it in 2016?
what was, then, the change over the year?
and over the subsequent year, what was this change?

Answers:
15.7%
15.1%
.6%
-.6%