Myrna and Geoffrey filed a joint tax return in 2015. Their AGI was $103,325, and itemized deductions were $19,200, which included $15,360 in state income tax. In 2016, they received a $9,216 refund of the state income taxes that they paid in 2015. The standard deduction for married filing jointly in 2015 was $12,600.
Under the tax benefit rule, $(_____) of the state income tax refund is included in gross income in 2016.