How old was Mavis Fan when she sang healthy songs?

Health Song is a children's song of 1989. Mavis Fan, a Wuhan "Little Witch" who grew up in Taiwan on 1996, was included in the famous album "Magic Book of Little Witch", and then the health song was shown to you on the Spring Festival Evening of 1998. So, Mavis Fan sang a health song at the age of 12, and became famous at the age of 18. At the age of 20, he took this song to the Spring Festival Evening.