An appraiser can research sales in 2001 that would help establish the appraised value at that tme.
A Realtor can help too. Although a Realtor does not do appraisals unless he/she is licensed as an appraiser. Most people who are trying to determine values from previous years are often doing it for tax reasons, estate or divorce separation reasons. Normally, when there is a legal issue involved it is highly recommended. (by me and others) to choose to have an appraisal because it is believed to have more value if there is ever a tax audit or legal challenge. This is because appraisers are utilizing a more "scientific form" than a Realtor who can choose various forms and whose opinion is easier to challenge as a result of that. This does not mean that the Realtor is any less accurate and, in fact, the person could be more accurate than the appraiser. Choose based on what you think serves your purpose best.