At the beginning of 2016, Gannon Company received a three-year zero-interest-bearing $1,000 trade note. The market rate for equivalent notes was 8% at that time. Gannon reported this note as a $1,000 trade note receivable on its 2016 year-end statement of financial position and $1,000 as sales revenue for 2016. What effect did this accounting for the note have on Gannon's net earnings for 2016, 2017, 2018, and its retained earnings at the end of 2018, respectively?