Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
OPERATING ACTIVITIES
Net income	$ 8,559,914	$ 11,160,145
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	386,968	403,691
Stock-based compensation	41,297	48,360
Deferred income taxes	(73,269)	71,800
Changes in operating assets and liabilities:
Accounts receivable	(467,290)	876,601
Inventories	41,973	105,134
Prepaid expenses and other assets	181,557	80,746
Accounts payable and other liabilities	(140,082)	(210,172)
Net cash provided by operating activities	8,531,068	12,536,305
INVESTING ACTIVITIES
Purchases of fixed assets	(13,627)	(26,076)
Purchases of marketable securities		(7,196,330)
Proceeds from maturities of marketable securities	12,000,000	12,500,000
Cash provided by investing activities	11,986,373	5,277,594
FINANCING ACTIVITIES
Repurchase of common stock	(91,419)
Payment of dividends to shareholders	(14,503,308)	(14,538,030)
Cash used in financing activities	(14,594,727)	(14,538,030)
Increase in cash and cash equivalents	5,922,714	3,275,869
Cash and cash equivalents at beginning of period	8,065,594	6,877,304
Cash and cash equivalents at end of period	13,988,308	10,153,173
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	$ 1,636,788	$ 1,931,661