Frequency Charts

Hey folks

Just curious as to the reason they graph out frequency charts as they do. What im refferring to is the fact that they Display 20 - 100hz on the first 1/4 of the chart, then 100hz to 1khz on the 2nd quarter, followed byu the 1k-10k, and lastly the 10-20k, meaning they graph out half of the hearing range in the last 1/4

i guess this is a kind of a dumb question, it just seems that by reading the first half of the graph covers just 1/20th of the range while the other 19/20th's are all crammed together.

i know that it would be pretty difficult to put a graph in a magazine of 20,000 without using some technique to compact it. Is there any logical reason that group it out the way they do other than to save space?