How do I remove Etag from IIS7.5

I just want to optimize my asp.net web site which is hosted on IIS 7.5 web server. I have tried all the below methods using asp.net web.config file. But none of working. Please help me to resolve this.

<httpProtocol><customHeaders><remove name="ETag" /></customHeaders></httpProtocol>

<httpProtocol><customHeaders><addname="ETag"value=""/></customHeaders></httpProtocol>

<httpProtocol><customHeaders><addname="ETag"value="&quot;&quot;"/></customHeaders></httpProtocol>