PHP - Reducing Sql Value By One

Hi Guys and Gals,

I run a simple fansite for some of my fellow MTG Tactics players at www.onlinegamekey.com

I recently made a Booster Page value page he http://www.onlinegamekey.com/booster-packs.php

And it seems the page loads really slow, but I kind of understand that since its doing a lot of math and dealing with a lot of data.

I am wondering if there is a way to possibly optimize the page and querys in such a way that it doesn't take so long to load.

I'm basically using 4 queries to get the value of each pack and 1 function to average the query data. And I add them up as I go.

This is my function to find average values
Code: [Select]
///AVERAGE FUNCTION
function calculate_average($arr) {
    $count = count($arr); //total numbers in array
    foreach ($arr as $value) {
        $total = $total + $value; // total value of array numbers
    }
    $average = ($total/$count); // get average value
    return $average;
}
These are the queries to get the Average Values
Code: [Select]
<?php
///SETTING THE DAY
$today = date("Y/m/d");
///ALTERING DAY QUERY TIME (20 Days of Data)
$minusday = mktime(0,0,0,date("m"),date("d")-20,date("Y"));
///SETTING THE DAY FOR THE QUERIES
$queryday = date("Y/m/d",$minusday);

///DATA SET FOR BOOSTER PACK 1
//GET THE MYTHIC AVERAGE VALUE
$sqlMythic=mysql_query("SELECT AVG( ab.Price_Per ) AS Aaverage
FROM auctions AS ab
INNER JOIN cardlist AS c ON c.card_name = ab.Card_Name
WHERE ab.Day >= '$queryday'
AND c.rarity = 'Mythic Rare'
AND c.set = '1'
GROUP BY c.card_name, ab.Card_Name") or die;
while ($row=mysql_fetch_array($sqlMythic)) {
$MythicValues[]=$row['Aaverage'];
}
///MYTHIC VALUE IS 10% OF AVERAGE VALUE
$Mythic = calculate_average($MythicValues) * .1;

//GET THE RARE AVERAGE VALUE
$sqlRare=mysql_query("SELECT AVG( ab.Price_Per ) AS Aaverage
FROM auctions AS ab
INNER JOIN cardlist AS c ON c.card_name = ab.Card_Name
WHERE ab.Day >= '$queryday'
AND c.rarity = 'Rare'
AND c.set='1'
GROUP BY c.card_name, ab.Card_Name") or die;
while ($row=mysql_fetch_array($sqlRare)) {
$RareValues[]=$row['Aaverage'];
}
///RARE VALUE IS 90% OF AVERAGE RARE VALUE
$Rare = calculate_average($RareValues) *.9;
///TOTAL CONTRIBUTION TO PACK 100% IS 10% MYTHIC + 90% RARE
$raremythic= $Mythic + $Rare;

///GET THE UNCOMMON AVERAGE VALUE
$sqlUncommon=mysql_query("SELECT AVG( ab.Price_Per ) AS Aaverage
FROM auctions AS ab
INNER JOIN cardlist AS c ON c.card_name = ab.Card_Name
WHERE ab.Day >= '$queryday'
AND c.rarity = 'Uncommon'
AND c.set='1'
GROUP BY c.card_name, ab.Card_Name") or die;
while ($row=mysql_fetch_array($sqlUncommon)) {
$ucValues[]=$row['Aaverage'];
}
///UNCOMMON VALUE IS VALUE * 3
$Uncommon = calculate_average($ucValues);
$urm= ($Uncommon * 3) + $raremythic;

///GET THE COMMON VALUE
$sqlCommon=mysql_query("SELECT AVG( ab.Price_Per ) AS Aaverage
FROM auctions AS ab
INNER JOIN cardlist AS c ON c.card_name = ab.Card_Name
WHERE ab.Day >= '$queryday'
AND c.rarity = 'Common'
AND c.set='1'
GROUP BY c.card_name, ab.Card_Name") or die;
while ($row=mysql_fetch_array($sqlCommon)) {
$cValues[]=$row['Aaverage'];
}
///COMMON VALUE IS VALUE * 10
$common = calculate_average($cValues);
//TOTAL SET 1 VALUE IS ALL VALUES ADDED UP
$curm= ($common * 10) + $urm;
?>
But I'm not real sure where the strain is coming from. The page seems to load really slow, and I'm not sure if I should just try and write all these queries as a separate function then have it write the data to a separate table, or if there is another way to optimize this code.

I'm still have a lot to learn so I would appreciate any thoughts or ideas you folks can offer me.

Many thanks