In early 2015 , Ford Motor (F) had a book value of equity of $24.8 billion, 4.0 billion shares outstanding, and a market price of $16.00 per share. Ford also had cash of $21.7 billion, and total debt of $119.2 billion. Three years later, in early 2018 , Ford had a book value of equity of $35.0 billion, 10.0 billion shares outstanding with a market price of $11.0 per share, cash of $26.5 billion, and total debt of $154.3 billion. Over this period, what was the change in Ford's market debt - equity ratio from 2015-2018 ?