Simplify the following text for a Grade 10 native English-speaking person.
Original: Several economic studies and legal decisions of antitrust authorities have found that the median price increase achieved by cartels in the last 200 years is around 25 % .
Simplified: A survey was done of hundreds of published economic studies and legal decisions of antitrust authorities . It found that the median price increase achieved by cartels in the last 200 years is 25 % .