Apex trigger for Number of Time Record is Viewed

Question

I am trying to develop an Apex trigger for an Object Lead. Requirement is like count number of times that record viewed.

I am Sharing my Code with you.

trigger ContactedRecord on Lead (after insert,after update) {

List<ID> lid=new List<ID>();

for(Lead l:Trigger.new)
{
    lid.add(l.id);
}

Integer i=0;
List<Lead> leadlist=[Select id,No_of_Times_Contacted__c from Lead where id IN:lid];

System.debug('**List size**'+leadlist.size());

for(Lead li: leadlist)
{
    /*Lead l=new Lead();
    Lead olddata=Trigger.oldMap.get(li.id);*/

    system.debug('No of Contacts');

    if(li.size()>0)
    {
        for(Integer j=0;j<li.Size(0);j++)
        {
            if(li.No_of_Times_Contacted__c ==li[j].id)
            {
                i++;
                li[j].No_of_Times_Contacted__c =i;
            }
        }
    }

    update li;
}