A sobering historical analysis of today's stock market levels

Following the recent Corona crash/rally, I was wondering if this is - historically - a good moment to buy for the long term. The conclusions are rather sobering.

• The red line represents the exponential curve that has 20% of all the monthly closing points of the DOW (since 1915) above it, and 80% below it.
  
• The blue line represents the exponential curve that has 50% of all the monthly closing points of the DOW (since 1915) above it, and 50% below it. It is, therefore, the median growth curve for the DOW over the past 105 years.
  
• The green line represents the exponential curve that has 80% of all the monthly closing points of the DOW (since 1915) above it, and 20% below it.
  

Comment:

I had a comment that, if I had taken the DOW closing price of dec 1917 (100% higher!!) instead of the closing price of dec 1914, the three curves would have ended up much higher, displaying the present prices below the blue or even the green line.

Well, that argument is false. If I had started in dec 1917, I would have needed to adjust the exponential base of the blue (and the red and green) curve of the three curves. Remember that the criterion for establishing the blue curve is always that it has 50% of the closing on top, and 50% below, regardless what the starting point is. The two blue curves would be almost indistinguishible from each other.

It is the length of the considered period (105 years) that determines the validity of the analysis, not the level of the starting point.

Comment:

A pity I can't change the title. It shouldn't be "today's stockmarket levels" but "post-corona-crash stockmarket levels". If anyone knows how to change the title, please let me know.