Australia seems to have good wages because of their population but thats not the reasn why most people in the Australia like to gamble. However, gambling seem to be vital part of Australian society from the early days and thats the reason why they have more game machine (which can be see almost everywhere) than any country in the world.
2double0, the link provided by the OP is outdated and i think US and China are the leading countries now.
If we will be talking about gambling as being a Vital Part ,then it must be Chinese because they seems to be One of the oldest Gambling Founding in the world, and also one of the oldest Civilization ever recorded .
So it is still the Wage that matters because even How they love gambling but if the funds are limited i don't think they will engaged more,and also i believe that Gambling was Only Brought to AUstralia when the British Colony transported the Penal colony .
I dont know about Norway but Ireland is also among the country in the world that love gambling and they are mostly into the sport betting. But gambling is like a culture in Australia and it also generates good tax for their government and statistics show that 80% of Australian adult are into gambling
Actually talking about Culture and the percentage of adult that engaging in gambling ,it is from Asia ,because almost every individual and even kids are into gambling though wasnt recorded because the statistics based only in Casino attendance and not in Street gambling and illegal gambling ,things that most adults from asia plays to stay away from obligation in taxes and any sort of hindrances .