Something from an unknown date (I assume the 1970 mentioned is wrong, since it's talking about events in the 90s and 00s, but with time travel technology one can never be too sure):
https://resource.wur.nl/nl/show/Nationaal-kampioene-stopt-met-ritmische-gymnastiek.htm
It's about a triple Dutch champion retiring. It says she became Dutch champion in 2000 for the first time, winning all events, and a year later doing the same. However, KNGU (gymnastics federation) then decided to stop the whole rhythmic gymnastics national team to focus all resources in women's artistic gymnastics. Van Montfoort says her coach (a Bulgarian who was world champion herself) got fired and she had to go train at her local team. She and some others kept on going because the 2003 world champs were supposed to be held in the Netherlands, but eventually they retired.