Note 6 - Share Based Compensation - Stock Option Exercises (Details) - $ / shares	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Number of stock options exercised (in shares)	0	54,705
Exercised, weighted average exercise price per share (in dollars per share)	$ 0	$ 2.30

Number of share options (or share units) exercised during the current period.

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