need to show a graph from mongodb data
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I would like to know what is the best way to do the following.

I store data of what a person has done in mongodb like a log

e.g.

    {
     "date":"01-01-2002T08:20:30",
     "task":"contact-lead",
     "user":"username"
    }

what I need is to count how many tasks where done in that day and put them in a graph like Highstock there site http://www.highcharts.com/stock/demo/

Please help if you know how to do this.