Can someone help me with something please.  Which of the following is correct:
Ten year's service
Ten years service
Ten years' service
Context: In recognition of his ten (years/year's/years') service with the company they gave him a gift
I am erring towards ten year's service but I have consistently seen it written all three ways.
Thanks
				
			Ten year's service
Ten years service
Ten years' service
Context: In recognition of his ten (years/year's/years') service with the company they gave him a gift
I am erring towards ten year's service but I have consistently seen it written all three ways.
Thanks
 
				 
						
 
 
		 
 
		 (actually it's quite sad, so:
  (actually it's quite sad, so:  
 
		 
 
		 
 
		 
 
		 
 