For all BAI polymer $20 prefixes, the notes are skip numbered by 50,000 from 0000000 to 8999999 and by 22,000 from 9000000 to 9989999. No notes above this point have been reported yet.
As for the missing positions, your data does seem anomalous. The SNDB (currently) has 48,144 notes from these prefixes and reports a fairly even distribution across all 45 positions with the low (99) being 985 notes, the high (63) being 1,156 notes and the average being 1,070. Even broken down by prefix, the data remains fairly homogeneous with nothing really sicking out as being a "rare" prefix/position pair. All positions are represented for each prefix.
Would you care to add your data to the SNDB so that it can be used together with what's already there? Your most recently entered note was from January.
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BWJM, F.O.N.A.
Life Member of CPMS, RCNA, ONA, ANA, IBNS, WCS.
President, IBNS Ontario Chapter.
Treasurer, Waterloo Coin Society.
Show Chair, Cambridge Coin Show.
Fellow of the Ontario Numismatic Association.