QUALIFYING ACCOUNTS (Details) - Allowance for doubtful accounts - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Valuation and Qualifying Accounts
Balance at Beginning of Period	$ 372,828	$ 366,105	$ 343,805
Additions, Charged to Costs and Expenses	365,746	201,622	308,401
Deductions	215,570	194,899	286,101
Balance at end of Period	$ 523,004	$ 372,828	$ 366,105