Following a 1992 change in which the FCC abandoned a one-to-a-market limit on radio station ownership, new ownership rules allowed ownership of multiple stations, with the exact number depending on market size, up to 25% of audience share. The Telecommunications Act of 1996 then directed the FCC to further relax ownership limits, allowing up to eight stations in a market (no more than five in the same FM or AM), and to review the rules biennially. Following the 2002 Biennial Review, the FCC decided to change the meaning of 'radio market' from a contour-overlap methodology, to a geography based method used by Arbitron. At the same time as switching to Arbitron Radio Markets, the FCC decided to begin including non-commercial stations when determining the size of the market. These two changes somewhat offset each other, since switching to geography reduced the size of markets, while adding non-commercial stations increased the size, however, on average, the net effect was a slight decrease in market size. In applying these new rules, current ownership configurations that would be found impermissible once new rules took effect were grandfathered their existing ties.