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Stock Option Plans (Tables)
6 Months Ended
Jun. 30, 2020
Stock Option Plans  
Summary of stock option activity

Options Outstanding

    

    

    

Weighted 

Shares

Average

Available

Number of 

Exercise

    

for Grant

    

Options

    

Price

Balance at December 31, 2019

 

1,704,183

 

5,643,410

$

8.05

Additional shares authorized

 

1,118,000

 

 

Options granted

 

(190,000)

 

190,000

 

2.68

Options exercised

 

 

(81,500)

 

0.28

Options forfeited

 

190,812

 

(190,812)

 

7.07

Balance at June 30, 2020

 

2,822,995

 

5,561,098

$

8.01