I don't think I am, but I could be wrong (as always). Specifically I'm talking about yield to maturity which is one kind of return calculation (just like mean is one type of average calculation).
Total return can only be calculated after the fact once capital gains are factored in. Since this is a forward-looking calculation we can't do that. I'm using the term "yield", more specifically "yield to maturity" because I'm assuming bonds were held until maturity. In that situation yield to maturity should be the same as total return; ie, total return is equal to yield to maturity in the special case that there are no capital gains or losses and the bond is held to maturity. So in this case I'm not conflating them, they are the same thing.
Yield to maturity is based on par value, coupon rate, term, and purchase price. The yield to maturity formula is:
YTM = (C + ((F-P) / n)) / ((F+P) / 2)
Where C = coupon, F = Face/par, P = price, n = years to maturity.
Looking up historical data for Apr 2016 you get P = $137 (secondary) and C = 1.7%. Plug it all in and you get a yield to maturity / rate of return of -1.7%.
