Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Preferred stock, issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	500,000,000	500,000,000
Common stock, issued (in shares)	45,909,466	44,292,722
Common stock, outstanding (in shares)	45,909,466	44,292,722

Face amount or stated value per share of common stock.

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