The yield-to-maturity for Treasuries of different maturities is as follows: 1.5% for 5 years, 2% for 10 years, and 3% for 20 years. Is the yield curve upward sloping, flat, or downward sloping? Based on theories discussed in class (expectations and liquidity), explain one possible reason for the shape of the yield curve. Be specific, using content discussed in class.