> To be clear, it all depends on what you count. If you're counting units sold, you can double your count by selling everyone 1 unit, then 2, then 4, etc. (In Finland I understand that cell phone usage is above 1 per capita, but still growing.) If you're counting the total number of households that own the product, you can double your count by doubling the population, or by convincing everyone to divorce and become two households. But if you're counting percentage of people (or households), there's just no more doubling after you pass 50%.
> To be clear, it all depends on what you count. If you're counting units sold, you can double your count by selling everyone 1 unit, then 2, then 4, etc. (In Finland I understand that cell phone usage is above 1 per capita, but still growing.) If you're counting the total number of households that own the product, you can double your count by doubling the population, or by convincing everyone to divorce and become two households. But if you're counting percentage of people (or households), there's just no more doubling after you pass 50%.