So, my process could be revised as what I did to create the graph:
...
In the last 20 years,
Cheapest 15% of the time: Two year forward real total return average 17.8%/year
Next 15% of the time: Two year forward real total return average 14.8%/year
Next 20% of the time: Two year forward real total return average 10.0%/year (just a little cheaper than average)
Next 20% of the time: Two year forward real total return average 8.7%/year (just a little more expensive than average)
Next 15% of the time: Two year forward real total return average 0.6%/year
Most expensive 15% of the time: Two year forward real total return average -5.4%/year


PS

In the context of my suggested mechanical strategy using a value line like this:

When things are expensive, and returns have been on average negative, you'd be selling at the money or even in the money calls for quite high premiums, while selling very low strike puts for very low premiums. (still, it's money, and pretty much risk free). So long as the price remains high your high strike calls would probably get exercised, perhaps repeatedly, but you'd be gathering time value each time. When the stock eventually falls in valuation level, you'd keep the whole premium, which would sometimes include some in-the-money premium and be quite lucrative. That's more or less the situation I've found myself in these last couple of months.

As the list above shows, when valuations are high the subsequent *average* return is likely pretty low. The price and valuation level might stay high for a while, but sooner or later you're likely to see "the usual".

Jim