Original sentence: European Championships.The European Racquetball Championships are organized by the European Racquetball Federation (ERF) every two years, since 1981, to determine the strongest national racquetball team in Europe
Edited sentence: European Racquetball Championships.The European Racquetball Championships are organized every two years by the European Racquetball Federation (ERF), since 1981, to determine the strongest national racquetball teams in Europe