What is the ratio (including both short-term and long-term) of the cost from the U.S. Treasury securities to corporate debt securities in 2019?
{"Available-for-sale securities: -- U.S. Treasury, short-term": {"Cost": 4240, "Gross Unrealized Gains": 2, "Gross Unrealized Losses": "$\u2014", "Fair Market Value": 4242}, "Available-for-sale securities: -- Corporate debt securities, short-term": {"Cost": 12258, "Gross Unrealized Gains": 2, "Gross Unrealized Losses": "\u2014", "Fair Market Value": 12260}, "Available-for-sale securities: -- U.S. Treasury, long-term": {"Cost": 1102, "Gross Unrealized Gains": "\u2014", "Gross Unrealized Losses": -1, "Fair Market Value": 1101}, "Available-for-sale securities: -- Corporate debt securities, long-term": {"Cost": 451, "Gross Unrealized Gains": "\u2014", "Gross Unrealized Losses": "\u2014", "Fair Market Value": 451}, "Available-for-sale securities: -- Total": {"Cost": 18051, "Gross Unrealized Gains": 4, "Gross Unrealized Losses": -1, "Fair Market Value": 18054}}
us_treasury_shortterm = df["Available-for-sale securities: -- U.S. Treasury, short-term"]["Cost"]
us_treasury_longterm = df["Available-for-sale securities: -- U.S. Treasury, long-term"]["Cost"]
corporate_debt_shortterm = df["Available-for-sale securities: -- Corporate debt securities, short-term"]["Cost"]
corporate_debt_longterm = df["Available-for-sale securities: -- Corporate debt securities, long-term"]["Cost"]
answer = (us_treasury_shortterm + us_treasury_longterm) / (corporate_debt_shortterm + corporate_debt_longterm)