Easy Lime Pie

1 9 inch lowfat graham cracker crust
1 14 oz can nonfat sweetened condensed milk
1 6 oz can limeade concentrate, thawed
1/4 cup key lime juice
1 8 oz carton lite cool whip
1 or 2 drops green food coloring if desired

Mix nonfat sweetened condensed milk with thawed limeade concentrate. Stir in lime juice and food coloring (if using). Fold in thawed lite cool whip. Pour into pie crust. Freeze