$(function(){
    var b=false;
    
    $('.annee1')
    .mouseover(function(){
        $(this).attr('src','images/logos/annee3.png');
    })
    .mouseout(function(){
        $(this).attr('src','images/logos/annee1.png');
    })    
    .click(function(){
        if(!b) $('.agenda').css({'visibility':'visible'})
        else $('.agenda').css({'visibility':'hidden'})
        b=!b;
    });
});