Note 5 - Stock-based Compensation (Tables)

12 Months Ended

Mar. 31, 2022

Notes Tables

Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Year Ended March 31
	2022			2021
Risk-free interest rate	0.7	–	0.9%	0.2	–	0.4%
Expected volatility	35	–	36%	34	–	35%
Expected life (years)		4.6			4.6
Dividend yield	5.0	–	5.4%	7.0	–	7.4%

Share-Based Payment Arrangement, Option, Exercise Price Range [Table Text Block]

Ranges of Exercise Prices			Number Outstanding		Weighted Average Exercise Price		Weighted Remaining Contractual Life (years)
$49.86	–	$57.46		17,500	$	55.94		4.0
$67.65	–	$107.86		11,500		78.44		5.7
				29,000	$	69.52		5.0

Share-Based Payment Arrangement, Activity [Table Text Block]

	Option Shares Reserved			Options Outstanding			Weighted Average Option Exercise Price
At March 31, 2019		135,230			22,000		$	70.89
Granted		(4,000	)		4,000		$	67.65
Exercised		-			(2,000	)	$	56.18
At March 31, 2020		131,230			24,000		$	71.58
Granted		(6,500	)		6,500		$	56.12
At March 31, 2021		124,730			30,500		$	68.28
Granted		(6,500	)		6,500		$	74.22
Exercised		5,000			(5,000	)	$	61.36
Terminated		3,000			(3,000	)	$	80.75
At March 31, 2022		126,230			29,000		$	69.52