Interestingly, when I did my PPL in 1973, 1 hr dual in a C172 (near new!) was $20 - about one days pay on the average wage ($5000 pa).
Fast forward to 2015 and, from the figures quoted above, 1 hr dual in a C172 is $300 - about one days pay on the average wage ($75,000 pa).
Go figure!
Dr 