Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Dec. 31, 2016		Dec. 31, 2015
OPERATING ACTIVITIES
Net income	$ 9,921,486		$ 9,691,472
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	868,218		628,186
Stock-based compensation	22,000		21,160
Excess tax deficiencies (benefits)	293		(352,294)
Deferred income taxes	(61,076)		305,391
Changes in operating assets and liabilities:
Accounts receivable	782,427		1,210,285
Inventories	42,755		633,581
Prepaid expenses and other assets	(16,909)		(328,655)
Accounts payable and accrued expenses	162,906		(625,422)
Deferred revenue	(714,805)		714,805
Net cash provided by operating activities	11,007,295		11,898,509
INVESTING ACTIVITIES
Purchases of fixed assets	(200,447)		(177,449)
Purchases of marketable securities	(11,528,240)		(9,613,052)
Proceeds from maturities of marketable securities	11,400,000		7,825,000
Net cash used in investing activities	(328,687)		(1,965,501)
FINANCING ACTIVITIES
Proceeds from sale of common stock	92,310		292,909
Excess tax (deficiencies) benefits	(293)		352,294
Repurchase of common stock			(1,851,290)
Payment of dividends to shareholders	(14,506,030)		(14,570,019)
Net cash used in financing activities	(14,414,013)		(15,776,106)
Decrease in cash and cash equivalents	(3,735,405)		(5,843,098)
Cash and cash equivalents at beginning of period	7,534,593	[1]	9,437,262
Cash and cash equivalents at end of period	3,799,188		3,594,164
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	$ 4,720,000		$ 4,490,000

[1] The March 31, 2016 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, 2016.