def mean_otu_pct_abundance(ra, otuIDs):
sids = ra.keys()<EOL>otumeans = defaultdict(int)<EOL>for oid in otuIDs:<EOL><INDENT>otumeans[oid] = sum([ra[sid][oid] for sid in sids<EOL>if oid in ra[sid]]) / len(sids) * <NUM_LIT:100><EOL><DEDENT>return otumeans<EOL>
Calculate the mean OTU abundance percentage.

:type ra: Dict
:param ra: 'ra' refers to a dictionary keyed on SampleIDs, and the values are
           dictionaries keyed on OTUID's and their values represent the relative
           abundance of that OTUID in that SampleID. 'ra' is the output of
           relative_abundance() function.

:type otuIDs: List
:param otuIDs: A list of OTUID's for which the percentage abundance needs to be
               measured.

:rtype: dict
:return: A dictionary of OTUID and their percent relative abundance as key/value pair.