The bar graph illustrates the number of people take part in the fitness of the act from 1985 to 2015 in Thai LAN. --> the bar chart compares the number of ... illustrates is ok, but compares is better
Overview, it is clear that the amount of male and female was highest in 2010 (only male). The number of males increased steadily between 1985 and 2015, while the female decreased.
In 1985, the amount of members man has about 2200, in contrast [you can also use however instead of in contrast] with the women only was 1300 members. However, five years later, the both of the group grew steadily, the amount of male was double the female, about 3800 members and 1900 members, respectively. In the last ten years next, the number of men decreased gradually, in contrast the account of women rose considerable approximate 4000 members.
From 2005 to 2010, the both of the groups increased sharply in 2010 with 2950 and 5000 people, respectively. In 2015, the number of females doubles the male, approximate [at] 2000 and 10000 inhabitants.