php - How do I get only the new tweets per request using Twitter API? -

i'm trying new tweets containing hashtag twitter api. thing i'm interested in number of new tweets each time request results. this:

10:20 am: 100 tweets containing #google  10:22 am: 130 tweets containing #google 

but right somehow results stay same. code:

php (tweets.php):

<?php   $json = file_get_contents('http://search.twitter.com/search.json?q=%23apple:)&include_entities=true&rpp=100', true); echo $json; ?>  

javascript:

function gettweets() {     var tweets = 0;     $.ajax({         url: "tweets.php",         crossdomain: true,         datatype: 'json'         }).done(function(data) {             $.each( data.results, function( key, value ) {                 console.log(value.entities);                 tweets++;              });      }); } $(document).ready(function() {      setinterval("gettweets()", 5000);  }); 

how can updates?

edit: code works, results not updates. same results on , on again.

$(document).ready(function() {      setinterval(function(){ gettweets();}, 5000);  });