This page is taking too long to load - php

Question

I have created a view page on php zend framework. View page has 10 methods. Each method has 3 sql queries returning thee values. I am calling these 10 methods 10 times. All queries is working on the table of 24,000 rows. It's taking 2-3 minutes to load the view page. I am storing the function results in arrays and using the array values to display.
How can I implement output caching on this?
Source code for my view part is:
Those are my variables:
$no_of_customers = array();
$no_of_customers_EE = array();
$no_of_customers_NEE = array();
$unique_customers = array();
$unique_customers_EE = array();
$unique_customers_NEE = array();
$no_of_sent = array();
$no_of_sent_EE = array();
$no_of_sent_NEE = array();
$no_of_opened = array();
$no_of_opened_EE = array();
$no_of_opened_NEE = array();
$no_of_surveys = array();
$no_of_surveys_EE = array();
$no_of_surveys_NEE = array();
$promoter = array();
$promoter_EE = array();
$promoter_NEE = array();
$detractor = array();
$detractor_EE = array();
$detractor_NEE = array();
$passive = array();
$passive_EE = array();
$passive_NEE = array();
one of the function i am using is
function unique_customer($con,$start_date,$end_date ,&$unique_customers,$i,$customerTable,&$unique_customers_EE,&$unique_customers_NEE)
{
$result = mysqli_query($con,"SELECT COUNT(DISTINCT emailAddress) AS Total, product FROM $customerTable WHERE importDate >='$start_date' AND importDate <'$end_date' ;");
$rs = mysqli_fetch_array($result);
$unique_customers[$i] = $rs['Total'];
unset($rs);
$result_EE = mysqli_query($con,"SELECT COUNT(DISTINCT emailAddress) AS Total_EE, product FROM $customerTable WHERE importDate >='$start_date' AND importDate <'$end_date' AND product = '';");
$rs_EE = mysqli_fetch_array($result_EE);
$unique_customers_EE[$i] = $rs_EE['Total_EE'];
unset($rs_EE);
$result_NEE = mysqli_query($con,"SELECT COUNT(DISTINCT emailAddress) AS Total_NEE, product FROM $customerTable WHERE importDate >='$start_date' AND importDate <'$end_date' AND product != '';");
$rs_NEE = mysqli_fetch_array($result_NEE);
$unique_customers_NEE[$i] = $rs_NEE['Total_NEE'];
unset($rs_NEE);
}
Calling these functions 10 times and storing the values in arrays