This topic interested me as I'm within days of being retired for 10 years. I've not had time to do some investigations until now, so late to the thread.
The calculations show the following:
Income -
Income in 2015 (retired) was only 61.5% of what income was in 2005 (working). European pensions pay back well.
Expenses -
Total cash out in 2015 is 60.5% of what cash out was in 2005.
Tax -
If we take tax out of the equation, cash out in 2015 is 85% of what was cash out (minus tax) in 2005. I live in Europe, and tax is high for higher incomes.
Lifestyle -
What I'm really attempting to find the answer to is have our spending habits changed? It doesn't feel like it. We paid off the mortgage on retirement, so if we take tax and mortgage expenses out of the equation, then what? Cash out in 2015 was 122% higher than cash out in 2005. With inflation, that doesn't come as a surprise.
Investments -
My only investments are, and always have been, cash in savings accounts (don't ask). The base rate in November 2007, in my country, was at 5.75%. By February of 2008, it had dropped to 0.5% and has stayed there ever since.
The 2005 projection for 2015 -
Straight up - the projection I made in 2005 for where I should be at the end of 2015 has proven to be wrong, by a more than a bit. In 2015 I had 15% more in savings than what was projected in 2005. Why? I'm still living below my means and saving roughly 20% each year, and my 2005 estimates were very conservative.
Don't be afraid, but plan, and adhere to the plan, well.
Edit: To be clear, total "cash in savings accounts" in 2015 have increased by 75% over what they were in 2005.