If an individual spends in the aggregate more than nine months of any taxable year in this State it will be presumed that he is a resident of this State. The presumption is not conclusive but may be overcome by satisfactory evidence that he is in the State for temporary or transitory purposes only. It does not follow, however, that a person is not a resident simply because he does not spend nine months of a particular taxable year in this State. On the contrary, a person may be a resident even though not in the State during any portion of the year.