All data has been derived from the transcriptions in the IGI derived from the official 1911 transcription - thus it is a transcription of a transcription of an earlier transcription !
Based on various Church, Civil and, post 1821, Decennial Census data
Note the figure of 499 for the 1757 headcount is an estimate by T Quayle based on interpolating between the 1726 and 1791 figures.
The register dates from 1622- the 1757 5-year average crude birth count of 21/year (ignoring outlier peak) corresponds to an estimated population of 630 (1757 census is 658). Like several other Manx parishes the IGI batch numbers are misleading (see Andreas), the gaps are due to not locating the correct batch number.
TBD - IGI batch numbers removed from pre 1800 marriages (see Andreas for details)
Several epidemic peaks can be noted. The missing years are 1835-1840.
R.A. Houston The Population History of Britain and Ireland 1500-1750, Macmillan Education Studies in Economic and Social History (ISBN 0-333-56564-9) 1992