 However, before interpreting the figures, it should be borne in mind that art is often exempt of many kinds of taxes.In 1986, Baumol made an estimate of an average yearly rate of return of 0.55 percent for works of art, against a rate of return of 2.5 percent for financial assets, over a 20-year period.Throughout many art auctions, the source of the money of the bidder is often hard to identify or the works are purchased by an anonymous buyer.