The hand sanitizer business was booming in 2020. Whereas the industry made $200 million in 2019, this number jumped to $1.4 billion in 2020. Industry analysts suggest that the same percent change happened for multi-purpose cleaners between 2019 and 2020. If the total revenue made by the multi-purpose cleaner industry was $3.5 billion in 2020, what was the revenue made by this industry in 2019