QUALIFYING ACCOUNTS (Details) - Allowance for doubtful accounts - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation and Qualifying Accounts
Balance at Beginning of Period	$ 532,161	$ 643,990	$ 523,004
Additions, Charged to Costs and Expenses	445,909	357,789	422,109
Deductions	737,959	469,618	301,123
Balance at end of Period	$ 240,111	$ 532,161	$ 643,990