Myrna and Geoffrey filed a joint tax return in 2017. Their AGI was $74,325, and itemized deductions were $22,800, which included $18,240 in state income tax. In 2018, they received a $10,944 refund of the state income taxes that they paid in 2017. The standard deduction for married filing jointly in 2017 was $12,700.

Under the tax benefit rule, $_________of the state income tax refund is included in gross income in 2018.