.50% ( 7.50 % ) notes is 103.750% ( 103.750 % ) of the principal amount , subject to a ratable decline after may 1 of the following year to 100% ( 100 % ) of the principal amount in 2010 and thereafter . the company may also redeem up to 35% ( 35 % ) of the 7.50% ( 7.50 % ) notes any time prior to february 1 , 2007 ( at a price equal to 107.50% ( 107