Sam, a calendar year taxpayer, purchased an annuity contract for $3,600 that would pay him $120 a month beginning on January 1, 2011. His expected return under the contract based on his life expectancy is $10,800. Assuming Sam received a total of $1,440 in payments during 2011, how much of this annuity income is included in Sam's gross income for 2011, using the general rule