inflation

In terms of comfort level, today's middle class will most likely surpass that of a medieval king. But it'll be too hasty of a conclusion just to say working a 9-5 job as a middle class is better than being a medieval king. It's an overly simplified analogy, but you get my point here: What we track and measure has a profound influence on our decision-making process, and it's important to make sure what we track is representative of our ultimate goal.