Note 4 - Net Income Per Share (Tables)
 9 Months Ended
Dec. 31, 2015
Notes Tables  
Schedule of Weighted Average Number of Shares [Table Text Block]
 
 
Quarter Ended Dec. 31
 
 
 
2015
 
 
2014
 
Weighted average common shares outstanding – basic
     4,844,845       4,857,953  
Dilutive effect of stock options
     2,125       18,121  
Shares used in computing net income per share – diluted
    4,846,970       4,876,074  
 
 
Nine Months Ended Dec. 31
 
 
 
2015
 
 
2014
 
Weighted average common shares outstanding – basic
     4,853,970       4,854,702  
Dilutive effect of stock options
     3,133       16,568  
Shares used in computing net income per share – diluted
    4,857,103       4,871,270