Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Dec. 31, 2018		Dec. 31, 2017
OPERATING ACTIVITIES
Net income	$ 11,649,064		$ 10,030,252
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	531,685		726,842
Stock-based compensation	93,360		40,920
Deferred income taxes	(30,648)		153,954
Changes in operating assets and liabilities:
Accounts receivable	171,051		1,270,936
Inventories	(491,042)		(238,028)
Prepaid expenses and other assets	(120,646)		(360,675)
Accounts payable and accrued expenses	(123,775)		(159,525)
Deferred revenue			(142,733)
Net cash provided by operating activities	11,679,049		11,321,943
INVESTING ACTIVITIES
Purchases of fixed assets	(68,265)		(604,755)
Purchases of marketable securities	(11,649,227)		(16,256,210)
Proceeds from maturities and sales of marketable securities	15,800,000		16,540,000
Net cash provided by (used in) investing activities	4,082,508		(320,965)
FINANCING ACTIVITIES
Proceeds from sale of common stock	217,940		51,040
Payment of dividends to shareholders	(14,528,030)		(14,523,030)
Net cash used in financing activities	(14,310,090)		(14,471,990)
Increase (decrease) in cash and cash equivalents	1,451,467		(3,471,012)
Cash and cash equivalents at beginning of period	4,755,082	[1]	8,199,364
Cash and cash equivalents at end of period	6,206,549		4,728,352
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	$ 2,696,045		$ 4,615,019

[1] The March 31, 2018 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, 2018.