Complex sentence: ARIA became the official Australian music chart in June 1988, succeeding the "Kent Music Report" which had been Australia's national charts since 1974 and from 1940-1973 in a retrospective fashion.
Split into simpler sentences: ARIA became the official Australian music chart in June 1988. The "Kent Music Report" had been Australia's national charts since 1974 and from 1940-1973 in a retrospective fashion.