Supply-Adjusted CDD accounts for the impact of time on the Coin Days Destroyed metric. Because coin days are accrued over time, the total potential CDD increases over time. As such, adjusting for supply (an increase in the number of coins in circulation over time) in the denominator provides a more proportional view of dormancy over the history of a market.
Supply-Adjusted CDD simply divides CDD by the circulating supply (total amount of coins issued).
Hans Hauge - Introducing Binary Adjusted BDD