Gold bar is the hour the light is worth shooting at that spot, and the percentage under it is how busy it usually is at that hour. So it is answering "will there be a crowd when I actually want to be there", which is the question that matters. The percentages are relative to that place's own busiest hour, not an absolute count. 50% at Merlion Park is a lot more people than 50% at Lorong Halus.