=MAX(FREQUENCY(IF(D2:D254=0,COUNTIF(OFFSET(D2,,,RO W(INDIRECT("1:"&ROWS(D2:
D254)))),"<"&0)),ROW(INDIRECT("1:"&ROWS(D2:D254)) )-1))

After calculating the max frequency of "0" occuring in a string of data, I
needed the ability to return the average occurrence of the "0"s.