You should likely download a PDF copy of any other year's tax return...those that are available, now while you have the chance. IF you used the Online tax software....only 2015 and later is available right now...but one year is removed each year, so next year, only 2016 and later will be available....etc...etc
Back those pdf's up on a removable flash drive too.
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IF you used the Desktop software for any of those years, then you can create a PDF for any year you still have the software loaded for...those PDFs should be generated every year (just after filing successfully)...and backed up off-computer too.