Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Sep. 30, 2017		Sep. 30, 2016
OPERATING ACTIVITIES
Net income	$ 6,458,650		$ 6,437,742
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	480,143		392,546
Stock-based compensation	40,920		22,000
Excess tax deficiencies			1,369
Deferred income taxes	(113,718)		(64,915)
Changes in operating assets and liabilities:
Accounts receivable	777,184		(1,124,084)
Inventories	(146,180)		296,352
Prepaid expenses and other assets	84,093		36,736
Accounts payable and accrued expenses	(122,053)		(674)
Deferred revenue	(142,733)		(330,928)
Net cash provided by operating activities	7,316,306		5,666,144
INVESTING ACTIVITIES
Purchases of fixed assets	(526,377)		(153,096)
Purchases of marketable securities	(12,138,960)		(6,928,028)
Proceeds from maturities and sales of marketable securities	11,940,000		9,200,000
Net cash (used in) provided by investing activities	(725,337)		2,118,876
FINANCING ACTIVITIES
Proceeds from sale of common stock			42,449
Excess tax deficiencies			(1,369)
Payment of dividends to shareholders	(9,682,020)		(9,670,020)
Net cash used in financing activities	(9,682,020)		(9,628,940)
Decrease in cash and cash equivalents	(3,091,051)		(1,843,920)
Cash and cash equivalents at beginning of period	8,199,364	[1]	7,534,593
Cash and cash equivalents at end of period	5,108,313		5,690,673
Supplemental disclosures of cash flow information:
Cash paid during the period for income taxes	$ 2,975,019		$ 3,045,000

[1] The March 31, 2017 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, 2017.