The supplemental .zip archive for this publication contains the following files. Spreadsheets were created using Excel 2019 (v16) and should be compatible with Excel 2007 and later. 1. Excel Add-in with functions for smoothing migration data Osier00_20200611.zip 0) Requires Windows OS and 32-bit Excel 2007 or later i) Unzip the file ii) Open Excel and install addin ExcelOSR\ExcelOSR.xla iii) Close and restart Excel iv) Help pages can be accessed via Osier dropdown menu on Add-ins tab. Recommend users select Manual Calculation Option in Excel Options->Formulas 2. Excel spreadsheet to produce a selection of figures in the main text of the article SmoothingExamples.xlsx 3. Basic meta-information about the data used in the publication data-metainfo.txt