Unaudited Condensed Consolidated Statements of Cash Flows - USD ($)	6 Months Ended
	Jun. 30, 2018		Jun. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 220,272,725		$ 186,092,688
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	55,908,679		50,428,320
Gain on disposal of assets	(130,647)		(83,667)
Loss on disposal of assets	10,544		286,318
Gain on sale of investments	(1,245,359)		(876,496)
Loss on sale of investments	529,484		37,718
Deferred income taxes	(2,743,537)		7,008,364
Stock-based compensation expense related to employee stock options, employee stock purchases and restricted stock	8,652,939		9,114,708
Change in operating assets and liabilities:
Accounts receivable, net	(8,284,592)		(17,658,594)
Inventories	4,389,930		(7,228,785)
Prepaid expenses and other	(9,171,506)		16,812,179
Accounts payable	16,885,979		2,957,299
Accrued liabilities, excluding dividends declared and short-term debt	7,309,915		16,667,667
Net cash provided by operating activities	292,384,554		263,557,719
Activity in available-for-sale securities:
Sales proceeds	53,822,336		2,179,926
Maturities and calls	21,884,000		12,100,000
Purchases	(177,243,275)		(17,216,593)
Plant and equipment additions	(51,860,448)		(56,218,870)
Proceeds from sale of plant and equipment	179,700		89,701
Decrease (increase) in other assets	(2,965,781)		1,783,574
Net cash used for investing activities	(156,183,468)		(57,282,262)
CASH FLOWS USED FOR FINANCING ACTIVITIES:
Repayment of debt	(54,875,000)		(68,750,000)
Issuance of common stock from stock plan transactions	52,996,593		21,929,900
Cash dividends paid	(58,152,113)		(51,796,194)
Repurchases of common stock	(349,205,921)		(73,556,886)
Net cash used for financing activities	(409,236,441)		(172,173,180)
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(273,035,355)		34,102,277
CASH AND CASH EQUIVALENTS, beginning of period	569,734,496	[1]	546,477,075
CASH AND CASH EQUIVALENTS, end of period	$ 296,699,141		$ 580,579,352

[1] The condensed consolidated balance sheet at December 31, 2017 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.3