Note 16: Operating Expenses

The research and development expenses are broken down as follows:


	December 31,
Research and development expenses	2015		2016		2017
	(thousands of Euros)
Personnel expenses		13,268		32,777		37,112
Sub-contracting, collaboration, and consultants		15,325		34,413		54,397
Research supplies		911		1,234		1,464
Rental		1,094		1,903		2,018
Conferences, travel expenses		1,233		2,387		2,807
Depreciation and amortization		1,000		1,141		2,424
Small equipments and other supplies		795		2,675		2,646
Others		608		2,298		2,364

Total research and development expenses		34,234		78,828		105,232

The sales and marketing expenses are broken down as follows:


	December 31,
Sales and marketing expenses	2015		2016		2017
	(thousands of Euros)
Personnel expenses		133		4,954		6,976
Fees		339		4,447		2,480
Marketing, tradeshows and travel expenses		20		1,393		5,984
Others		—		487		384

Total sales and marketing expenses		491		11,282		15,824

By nature, the breakdown of general and administrative expenses is as follows:


	December 31,
General and administrative expenses	2015		2016		2017
	(thousands of Euros)
Personnel expenses		8,768		22,613		19,742
Fees		4,234		7,701		10,347
Rental		305		501		584
Insurance policies		1,239		1,853		1,367
Corporate communication and travel expenses		1,010		1,136		1,599
Depreciation and amortization		74		181		422
Others		1,229		1,020		1,776

Total general and administrative expenses		16,859		35,005		35,837

Personnel Expenses

The Company had 242 employees at December 31, 2017, in comparison with 164 employees at December 31, 2016 and 91 employees at December 31, 2015.

The personnel expenses are broken down as follows:


	December 31,
	2015		2016		2017
	(thousands of Euros)
Wages and salaries		7,243		14,651		22,451
Social security contributions		3,193		3,903		7,157
Expenses for pension commitments		116		982		1,583
Employer contribution to bonus shares		1,198		6,456		1,857
Share-based payments		10,419		34,353		30,781

Total		22,168		60,345		63,830

The increase in personnel charges is partly due to the growth of the Company’s employees and the increase of the share-based payments linked to the global plans put in place during the second semester of 2015 and in 2016 (see Note 17).