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Other Income, Net (Details) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Other income, net      
Interest income $ 388,801 $ 238,106 $ 122,575
Realized gain (losses) on maturities of investments 10,764 (29,308) (6,761)
Foreign currency exchange losses (3,653) (15,261) (4,437)
Total other income, net $ 395,912 $ 193,537 $ 111,377