Statements of Cash Flows - USD ($)	12 Months Ended
	Mar. 31, 2020		Mar. 31, 2019
OPERATING ACTIVITIES
Net income	$ 14,526,642		$ 14,507,936
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	549,969		705,197
Stock-based compensation	48,360		93,360
Deferred income taxes	77,779		(31,269)
Changes in operating assets and liabilities:
Accounts receivable	301,620		(106,859)
Inventories	380,426		(614,437)
Prepaid expenses and other assets	(394,504)		(180,885)
Accounts payable and accrued expenses	405,481		(154,049)
Net cash provided by operating activities	15,895,773		14,218,994
INVESTING ACTIVITIES
Purchases of fixed assets	(52,041)		(68,265)
Purchases of marketable securities	(7,196,330)		(13,672,407)
Proceeds from maturities and sales of marketable securities	12,500,000		20,800,000
Net cash provided by investing activities	5,251,629		7,059,328
FINANCING ACTIVITIES
Proceeds from exercise of stock options	112,360		217,940
Repurchase of common stock	(687,432)
Payment of dividends to shareholders	(19,384,040)		(19,374,040)
Net cash used in financing activities	(19,959,112)		(19,156,100)
Increase in cash and cash equivalents	1,188,290		2,122,222
Cash and cash equivalents at beginning of year	6,877,304	[1]	4,755,082
Cash and cash equivalents at end of year	8,065,594		6,877,304	[1]
Supplemental disclosures of cash flow information:
Cash paid during the year for income taxes	$ 2,586,661		$ 3,426,045

[1] The March 31, 2019 Balance Sheet is derived from the audited financial statements contained in our Annual Report on Form 10-K for the fiscal year ended March 31, 2019.