Correct that chart isn't inflation adjusted.
I tend to only calculate inflation adjusted values/results point to point. Level the initial value to a index value of 1.0 and calculate the nominal gain-factor progression, say ending at 2.6, and calculate the inflation index change over the same period, so if the inflation index was 1.3 at the start, 1.7 at the end then the real gain = 2.6 * 1.3 / 1.7 = 1.99. I then annualise that. If for instance that 1.99 real gain occurred over 5 years = 1.99^(1/5) = 1.1473 annualised gain factor, which is 14.73% annualised real.
I do sometimes plot running real gains, in which case I have one column of nominal running gain factors and another column with the running inflation index and a third column formed by dividing the respective first column value by the second column value.
