That figure sounds right - if you're talking about prosecutors being punished.
A survey conducted by the Innocence Project, Innocence Project New Orleans, Resurrection After Exoneration and the Veritas Initiative looked at five diverse states over a five-year period (2004-2008) and identified 660 cases in which courts found prosecutors committed misconduct, such as tampering with key evidence, withholding evidence from the defendant or coercing a witness to give false testimony. [..] Of the 660 cases examined, only one prosecutor accused of misconduct was disciplined.
This is another reason why police officers should be required to carry malpractice insurance, that they pay for.