On December 31, 2018, a company had assets of $34 billion and stockholders' equity of $28 billion. That same company had assets of $50 billion and stockholders' equity of $12 billion as of December 31, 2019. During 2019, the company reported total sales revenue of $27 billion and total expenses of $25 billion. What is the company's debt-to-assets ratio on December 31, 2019