Commission Regulation (EC) No 2718/1999 of 20 December 1999 amending Regulation (EC) No 97/95 laying down detailed rules for the application of Council Regulation (EEC) No 1766/92 as regards the minimum price and compensatory payment to be paid to potato producers and of Council Regulation (EC) No 1868/94 establishing a quota system in relation to the production of potato starch