Different speed of scroll in HTML

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<marquee behavior="scroll" direction="left" scrollamount="1">Very slow...</marquee>
<marquee behavior="scroll" direction="left" scrollamount="10">Faster...</marquee>
<marquee behavior="scroll" direction="left" scrollamount="20">Fast...</marquee>
<marquee behavior="scroll" direction="left" scrollamount="50">Lightning!</marquee>