What was the change in the Dividend payments allocated to retained earnings (accumulated deficit) between 2017 and 2018?
{"Dividends per share declared": {"April 26, 2019": 1.6, "April 27, 2018": 0.8, "April 28, 2017": 0.76}, "Dividend payments allocated to additional paid-in capital": {"April 26, 2019": 403.0, "April 27, 2018": 106.0, "April 28, 2017": 88.0}, "Dividend payments allocated to retained earnings (accumulated deficit)": {"April 26, 2019": "$ \u2014", "April 27, 2018": 108.0, "April 28, 2017": 120.0}}
dividend_2018 = df["Dividend payments allocated to retained earnings (accumulated deficit)"]["April 27, 2018"]
dividend_2017 = df["Dividend payments allocated to retained earnings (accumulated deficit)"]["April 28, 2017"]
answer = dividend_2018 - dividend_2017