I have added pointLabels for each series and put show:false for each series except the last one.
seriesDefaults: {
renderer: $.jqplot.BarRenderer,
rendererOptions:{barMargin: 25},
pointLabels:{show:false,
stackedValue: true}
},
series:[
{
pointLabels:{show:false,
stackedValue: false}
},
{
pointLabels:{show:false,
stackedValue: false}
},
{
pointLabels:{show:true,
stackedValue: false}
},
]