On January 1, 2016 Ivanhoe Corporation granted 10900 options to key executives. Each option allows the executive to purchase one share of Ivanhoe's $5 par value common stock at a price of $19 per share. The options were exercisable within a 2 year period beginning January 1, 2018, if the grantee is still employed by the company at the time of the exercise. On the grant date, Ivanhoe's stock was trading at $25 per share, and a fair value option pricing model determines total compensation to be $433000.

On May 1, 2018 8720 options were exercised when the market price of Ivanhoe's stock was $30 per share. The remaining options lapsed in 2020 because executives decided not to exercise their options.

Prepare the necessary journal entries related to the stock option plan for years 2016 through 2020.