Note 8 - Loss Per Share - Shares Used in Basic and Diluted Loss Per Common Share Computations (Details) - USD ($)		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net loss attributable to common shareholders per common share: basic and diluted calculation		$ (2,573,932)	$ (3,577,378)	$ (6,462,645)	$ (8,106,695)
Weighted average shared used in computation - basic (in shares)	[1]	51,581,762	9,838,152	44,089,157	7,362,240
Effect of diluted stock options, warrants, and preferred stock (2) (in shares)		0	0	0	0
Weighted average common shares outstanding - diluted (in shares)		51,581,762	9,838,152	44,089,157	7,362,240
Loss per common share basic (in dollars per share)		$ (0.05)	$ (0.36)	$ (0.15)	$ (1.10)
Loss per common share diluted (in dollars per share)		$ (0.05)	$ (0.36)	$ (0.15)	$ (1.10)

[1] The following is a summary of the number of underlying shares outstanding at the end of the respective periods that have been excluded from the diluted calculations because the effect on loss per common share would have been anti-dilutive: