function _DateInterval( vv ) { 
    var bb = 140*24*60*60*1000; //140 days
    if( vv >= bb ) { //140 days < 5 months
        bb = 8766*60*60*1000;//1 year
        if( vv < bb         ) return( bb/12 );  // 1 year       //1 month
        if( vv < bb *2      ) return( bb/6 );   // 2 years      //2 month
        if( vv < bb *5/2    ) return( bb/4 );   // 2.5 years    //3 month
        if( vv < bb *5      ) return( bb/2 );   // 5 years      //6 month
        if( vv < bb *10     ) return( bb );     // 10 years     //1 year
        if( vv < bb *20     ) return( bb*2 );   // 20 years     //2 years
        if( vv < bb *50     ) return( bb*5 );   // 50 years     //5 years
        if( vv < bb *100    ) return( bb*10 );  // 100 years    //10 years
        if( vv < bb *200    ) return( bb*20 );  // 200 years    //20 years
        if( vv < bb *500    ) return( bb*50 );  // 500 years    //50 years
        return( bb*100 );                       //100 years
    }
    bb /= 2; //70 days
    if( vv >= bb ) return( bb/5 ); //14 days
    bb /= 2; //35 days
    if( vv >= bb ) return( bb/5 ); //7 days
    bb /= 7; bb *= 4; //20 days
    if( vv >= bb ) return( bb/5 ); //4 days
    bb /= 2; //10 days
    if( vv >= bb ) return( bb/5 ); //2 days
    bb /= 2; //5 days
    if( vv >= bb ) return( bb/5 ); //1 day
    bb /= 2; //2.5 days
    if( vv >= bb ) return( bb/5 ); //12 hours
    bb *= 3; bb /= 5; //1.5 day
    if( vv >= bb ) return( bb/6 ); //6 hours
    bb /= 2; //18 hours
    if( vv >= bb ) return( bb/6 ); //3 hours
    bb *= 2; bb /= 3; //12 hours
    if( vv >= bb ) return( bb/6 ); //2 hours
    bb /= 2; //6 hours
    if( vv >= bb ) return( bb/6 ); //1 hour
    bb /= 2; //3 hours
    if( vv >= bb ) return( bb/6 ); //30 mins
    bb /= 2; //1.5 hours
    if( vv >= bb ) return( bb/6 ); //15 mins
    bb *= 2; bb /= 3; //1 hour
    if( vv >= bb ) return( bb/6 ); //10 mins
    bb /= 3; //20 mins
    if( vv >= bb ) return( bb/4 ); //5 mins
    bb /= 2; //10 mins
    if( vv >= bb ) return( bb/5 ); //2 mins
    bb /= 2; //5 mins
    if( vv >= bb ) return( bb/5 ); //1 min
    bb *= 3; bb /= 2; //3 mins
    if( vv >= bb ) return( bb/6 ); //30 secs
    bb /= 2; //1.5 mins
    if( vv >= bb ) return( bb/6 ); //15 secs
    bb *= 2; bb /= 3; //1 min
    if( vv >= bb ) return( bb/6 ); //10 secs
    bb /= 3; //20 secs
    if( vv >= bb ) return( bb/4 ); //5 secs
    bb /= 2; //10 secs
    if( vv >= bb ) return( bb/5 ); //2 secs
    return( bb/10 ); //1 sec
}