What is the proportion of the company's total long term debt as a ratio of its total contractual cash obligations?
{"": {"Total": "", "Less than 1 year": "", "1-3 years": "(in millions of U.S. dollars)", "3-5 years": "", "More than 5 years": ""}, "Long-term debt": {"Total": 23, "Less than 1 year": 6, "1-3 years": 11, "3-5 years": 6, "More than 5 years": ""}, "Operating leases": {"Total": 3840, "Less than 1 year": 688, "1-3 years": 1114, "3-5 years": 792, "More than 5 years": 1246}, "Retirement obligations (2)": {"Total": 95, "Less than 1 year": 10, "1-3 years": 20, "3-5 years": 20, "More than 5 years": 44}, "Purchase obligations and other commitments (3)": {"Total": 286, "Less than 1 year": 206, "1-3 years": 61, "3-5 years": 12, "More than 5 years": 6}, "Total": {"Total": 4244, "Less than 1 year": 910, "1-3 years": 1206, "3-5 years": 830, "More than 5 years": 1296}}
longterm_debt_total = df["Long-term debt"]["Total"]
total_total = df["Total"]["Total"]
answer = ( longterm_debt_total / total_total ) * 100.0