(1) The Secretary, through the Bureau of Labor Statistics, shall conduct a study every two years of unemployment among each of the following categories of veterans:
(A) Special disabled veterans.
(B) Veterans of the Vietnam era who served in the Vietnam theater of operations during the Vietnam era.
(C) Veterans who served on active duty during the Vietnam era who did not serve in the Vietnam theater of operations.
(D) Veterans who served on active duty after the Vietnam era.
(E) Veterans discharged or released from active duty within four years of the applicable study.