Golf Murder

A murder has been committed. Police are called to an apartment and find a man standing, holding a 5-iron in his hands, looking at the lifeless body of a woman on the ground. The detective asks, 

"Sir, is that your wife?" 

"Yes." 

"Did you hit her with that golf club?" 

"Yes. Yes, I did," the man answers. He stifles a sob, drops the club and puts his hands on his head. 

"How many times did you hit her?" 

"I don't know. Five...six ...put me down for a five."