How do you check what aspect ratio the player is using to play the game?

Is there a way I can check in script what aspect ratio the player is using?

For example:

if(aspect.ratio.of.player == 16:9)
{
//do this
}

else if(aspect.ratio.of.player == 4:3)
{
//do this insteaad
}

etc. etc.

Thanks!

(float)Screen.width / (float)Screen.height;