function perc2color(perc) {
            var r, g, b = 0;
            if (perc < 50) {
                r = 255;
                g = Math.round(5.1 * perc);
            }
            else {
                g = 255;
                r = Math.round(510 - 5.10 * perc);
            }
            var h = r * 0x10000 + g * 0x100 + b * 0x1;
            return '#' + ('000000' + h.toString(16)).slice(-6);
        }