5.	Other Assets

Other assets consist of the following:

December 31,	2015			2014

Patents, at cost	$	6,322		$	6,113
Accumulated amortization		(3,629	)		(3,364	)
Deposits on capital items		16,839			19,011
Software development costs, at cost		2,057			2,057
Accumulated amortization		(1,792	)		(1,381	)
Other		2,994			3,111
	$	22,791		$	25,547

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, $0.3 million, and $0.2 million in 2015, 2014, and 2013, respectively. 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, $0.4 million, and $0.5 million in 2015, 2014, and 2013, respectively.