You've formatted a number eg.2005 as a date (yyyy) so it's converting the date number (2005) which is 27th June 1905, and only showing the year part (1905).
In the pivot table, go into the field settings for Year, and change the number format back to a plain number or
General).
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But I'm fairly sure you're using a fairly up-to-date version of Excel and you can dispense with your 2 added columns by grouping the
date column. I've added another example pivot table which is based only on source data columns A:G with such grouping.