Table: web_browser_usage_3
Columns: period
internet_explorer
firefox
chrome
safari
opera
other_mozilla
mobile

Question: What percentage of users were using mobile browsers during the period in which 2.62% were using Opera?
SQL: SELECT "mobile" FROM web_browser_usage_3 WHERE "opera" = '2.62%'

Question: What percentage of users were using mobile browsers during the period in which 9.00% were using Chrome?
SQL: SELECT "mobile" FROM web_browser_usage_3 WHERE "chrome" = '9.00%'

Question: What percentage of users were using Safari during the period in which 30.82% were using Firefox?
SQL: SELECT "safari" FROM web_browser_usage_3 WHERE "firefox" = '30.82%'

Question: What percentage of users were using Internet Explorer during the period in which 2.1% were using mobile browsers?
SQL: SELECT "internet_explorer" FROM web_browser_usage_3 WHERE "mobile" = '2.1%'

Question: What percentage of users were using other Mozilla browsers during the period in which 9.00% were using Chrome?
SQL: SELECT "other_mozilla" FROM web_browser_usage_3 WHERE "chrome" = '9.00%'