5.	Other Assets

Other assets consist of the following:

December 31,	2014			2013

Patents, at cost	$	6,113		$	5,401
Accumulated amortization		(3,364	)		(3,075	)
Deposits on capital items		19,011			14,091
Software development costs, at cost		2,057			2,057
Accumulated amortization		(1,381	)		(969	)
Investment in equity securities		-			259
Other		3,111			700
	$	25,547		$	18,464

The capitalized cost of patents is amortized using the straight-line method over their useful lives. The cost of patent amortization was $0.3 million in 2014 and $0.2 million in both 2013 and 2012. The estimated annual patent amortization cost for each of the next five years is $0.3 million. Costs incurred to maintain existing patents are charged to expense in the year incurred.

Software development costs were incurred to develop and implement an integrated ERP system prior to the time the system became operational. These costs are being amortized using the straight line method over a period of sixty months. Costs incurred subsequent to the system becoming operational are being expensed. The cost of software development cost amortization was $0.4 million, $0.5 million, and $0.4 million in 2014, 2013, and 2012, respectively.