My son is 21, a full-time college student and earned $30K in 2018 working internships to pay tuition in 2019/20. Must I pay >15K in expenses to claim him as a dependent?

My son's Bachelor level college program is 5 years and includes 3 semesters of internships, 2 semesters occurred in 2018 and he earned $30,000. The third internships will occur in 2019 and he will probably make ~$16K. I paid many of his room & board expenses but the total I paid does not exceed 50% of his 2018 income, i.e., $15K.  The monies he earned are being saved to pay his tuition for 2019 and 2020.  Even though he is 21 and a full-time student, does this level of income make me unable to claim him as a dependent?