Selected horizontal percentages of a base-year amount from Coastal Ltd.'s income statement are listed here:

_______________________________2018.............2017...............2016

Net sales...................................110%.............101%..............100%

Cost of goods sold...................105%..............111%.............100%

Operating expenses....................99%...............112%............100%

Income tax expense.................136%.................60%.............100%

Assuming that Coastal did not have any non-operating or irregular items, did its net income increase, decrease, or remain unchanged over the period from 2016 to 2018? Explain.