GUI text doesn't function properly?

while true do
	local text = "Welcome to Forever Build 2014!"
	for i = 1, #text do
	script.Parent.Text = script.Parent.Text..text:sub(i,i)
	wait(.1)
	end
	wait(5)
	local text = "This place last updated on July 12."
	for i = 1, #text do
	script.Parent.Text = script.Parent.Text..text:sub(i,i)
	wait(.1)
	end
	wait(5)
	local text = "Now there are two spawn points! Build on different sides of the map!"
	for i = 1, #text do
	script.Parent.Text = script.Parent.Text..text:sub(i,i)
	wait(.1)
	end
	wait(5)
	local text = "We hope you enjoy your experience! Have fun building!"
	for i = 1, #text do
	script.Parent.Text = script.Parent.Text..text:sub(i,i)
	wait(.1)
	end
	wait(5)
	local text = "Credit for the amazing Build v3.1.0 tool goes to kasuku. His tool makes your building experience possible!"
	for i = 1, #text do
	script.Parent.Text = script.Parent.Text..text:sub(i,i)
	wait(.1)
	end
	wait(5)
end

This script makes text appear in individual letters, like so:

H

He

Hel

Hell

Hello

However, when the wait(5) passes, instead of getting rid of the old text, it builds upon it, like so:

Hello

HelloH

HelloHe

HelloHel

HelloHell

HelloHello

Also, I think the script is a bit inefficient. Any way to fix this?

Darkness is pretty close to the right trail, except it's after every wait(5) you want to add the below script to erase previous text.

script.Parent.Text = ""

Do text:Destroy()