If anyone's interested. I found out how to scan for the percentage. It was quite easy. All the praise goes to the original creator of this script but here's the code to be able to scan by %
Code:
# Custom ATR Plot by 7of9 for BRT
# edited 3/20/19
input AtrAvgLength = 14;
def ATR = WildersAverage(TrueRange(high(period = aggregationPeriod.DAY), close(period = aggregationPeriod.DAY), low(period = aggregationPeriod.DAY)), AtrAvgLength);
def TodayHigh = Highest(high(period = aggregationPeriod.DAY), 1);
def TodayLow = Lowest(low(period = aggregationPeriod.DAY), 1);
def DTR = TodayHigh - TodayLow;
plot DTRpct = Round((DTR / ATR) * 100, 0);