Question: What is the state rank of the company with 6.8 billion in revenue?
Schema: create table table_21926985_2 (state_rank_by_revenue varchar, revenue__$billions__2012_estimate varchar, PRIMARY KEY (state_rank_by_revenue))
SQL: select state_rank_by_revenue from table_21926985_2 where revenue__$billions__2012_estimate = "6.8"