Is it possible to display actual years (e.g. 2006, 2007, etc) rather than the number of years since purchase?
Yes. Simply choose that option under the Preferences item of the Settings menu. Keep in mind when doing so that the financial model is still operating in integer years after purchase and is not aligned to specific financial or calendar years (as in the date of purchase is only used in the Tax Variation dialog) as the purpose of PIA is as a modelling tool not an accounting tool.
