The number of teenagers who vape has increased significantly over the past 5 years. Last year the federal government launched an advertising campaign to educate teens about the health risks around vaping. The data below shows vaping usage rates among teens for the past 9 months since the launch of the advertising campaign. Month 9 is the most recent month.

The government wants to reduce the rate of vaping to 11% or less. Using the least squares method, determine how many more months of the advertising campaign is needed to meet the goal. Enter your answer to 1 decimal place.

Month	Percent of Teens who Vape
1	21.8
2	22.5
3	21.6
4	20.9
5	20.0
6	19.8
7	19.5
8	18.8
9	18.5