Note 4 - Net Income Per Share (Tables)
 3 Months Ended
Jun. 30, 2016
Notes Tables  
Schedule of Weighted Average Number of Shares [Table Text Block]
 
 
Quarter Ended June 30
 
 
 
2016
 
 
2015
 
Weighted average common shares outstanding – basic
     4,835,010       4,854,841  
Dilutive effect of stock options
     2,085       6,007  
Shares used in computing net income per share – diluted
    4,837,095       4,860,848