Making a scatter plot with CFCHART

Question

I am trying to build a scatter plot with ColdFusion 9. The input for the x axis is numeric and not evenly spaced. Here's what I tried:

<cfquery name="qryData" datasource="#datasource#">
    SELECT x, y
    FROM data
</cfquery>

<cfchart format="png" xaxistype="scale">
    <cfchartseries type="scatter" query="qryData" itemcolumn="x" valuecolumn="y">
</cfchart>

This generates a graph with the x values in the same order as they are in the query, rather than in numerical order:

What do I need to change to get a real scatter plot with the x axis in numerical order and correctly spaced between values?