imc

There are $365$ days in a year, plus $1$ extra day if there is a Leap Day, which occurs on years that are multiples of $4$ (with a few exceptions that don't affect this problem). Therefore, the number of days between Leap Day $2004$ and Leap Day $2020$ is: $16\cdot 365+4\cdot 1=5844$ Since the days of the week repeat every $7$ days and $5844\equiv -1\mathrm{mod}7$, the day of the week Leap Day $2020$ occurs is the day of the week the day before Leap Day $2004$ occurs, which is $\boxed{\text{Saturday}}$.