Original: By sixteen, Hahn had completed the Curtis Institute's university requirements, but elected to remain for several years to pursue elective courses, until her graduation in May 1999 with a Bachelor of Music degree.
Simplified: By the age of sixteen, Hahn had completed the Curtis Institute's university requirements, but elected to remain at the Institute for several more years to pursue additional elective courses, until her graduation in May of 1999 with a Bachelor Of Music degree.