Most used media queries for smarthphones and tablets?

Right now, I'm using this one for tablets:

@media screen and (max-w开发者_开发知识库idth: 960px) {
}

and this one for smarthphones:

@media screen and (max-width: 480px) {
}

I want to keep it simple and use only two. What are the most used media queries for smarthphone and tablet?

I would use for mobile devices:

@media only screen 
and (min-device-width : 320px) 
and (max-device-width : 480px)

AND for tablets:

@media only screen 
and (min-device-width : 768px) 
and (max-device-width : 1024px)

Didn't see the date posted...a little out of date.