Northup was incorporated on January 1, 2012, and adopted a calendar year for tax purposes. It had the following gross receipts for its first six taxable years:

2012 .............................. $4,282,000

2013 .............................. 8,418,000

2014 .............................. 7,002,000

2015 .............................. 9,668,000

2016 .............................. 5,219,000

2017 .............................. 3,843,000

For which of these years is Northup exempt from AMT?