This is not a correct way to do maths...
If something raises 3000% from $1 to $3000 and then it loses 50%, it does actually have a value of $1500, so, put the number 3000 and 50 is a very bad indicator. It would be more correct to say "it went down from a raise of 3000% to a raise of 1500% since the beginning of the year"