cartography - How to normalize choropleth maps of census information?

I'm trying to improve on the census-based maps on this site, which shows census values at 5 scales from Collection Districts through to State.

Currently the maps show whole numbers (eg total population per polygon) which is not optimal. How should they be normalized?

Option 1: % of Total

I was advised to normalize by % of the total. This results in legend ranges such as "0.0004% to 0.0006% of the Total Population" which (IMO) make the legend hard to decipher - it's not an intuitive fraction, and is hard to put into perspective.

Option 2: Population Density

Another option could be to normalize based on area. Since the datasets are stored in meters, this also results in values like "0.000000019 to 0.000000035 persons per square meter".

I could flip this to show "area / person" - but this wouldn't make sense for datasets such as housing. And would it be offensive when applied to datasets such as religion (1km2 per X person)?

Is there a standard methodology to convert either of these values into something more meaningful? What do other people do on their census maps?

Thanks, Steve

Answer

Going with the % option, you could simply say "4 to 6 people in every million (1,000,000)" which means the same thing, but deals with nice round numbers (well, you're normalising to 1,000,000).