Remove borders for empty cells.

Sex	Name	Height
F	Alice	56.5
	Barbara	65.3
	Carol	62.8
	Jane	59.8
	Janet	62.5
	Joyce	51.3
	Judy	64.3
	Louise	56.3
	Mary	66.5
M	Alfred	69
	Henry	63.5
	James	57.3
	Jeffrey	62.5
	John	59
	Philip	72
	Robert	64.8
	Ronald	67
	Thomas	57.5
	William	66.5