* Canadian business lending index rises 5 pct in Q3 from Q2 * Borrowing rises 20 percent year over year * Sector growing twice as fast as U.S., says PayNet * Commercial loan delinquencies fall in 3rd quarter By Claire Sibonney TORONTO, Dec. 12 (Reuters) - Commercial borrowing by Canadian companies hit the highest level in the third quarter since early 2009, a PayNet survey showed on Wednesday, suggesting businesses played an outsized role in supporting the economy as growth