On 14 April 2016, Bombardier shares were at a six-month high based on then-unconfirmed rumours that Delta Air Lines had ordered the CSeries. On 28 April 2016, finally, Bombardier and Delta announced a sale for 75 CS100 firm orders and 50 options; the first aircraft should enter service in spring 2018. Delta would likely start using more fuel-efficient CS100s in 2018 on flights out of Los Angeles, New York and Dallas. Airways News believed that a substantial 65 to 70% discount off the $71.8 million list price was provided making the final sale at $24.6–28.7 million price per aircraft; this large order from a major carrier could help Bombardier to break the Boeing/Airbus duopoly on narrow-body aircraft. Boeing then filed a dumping petition for a total duty of 292% on the CSeries, which later initiated the partnership between Bombardier and Airbus.