It should be possible to choose and smooth line chart or a spline chart. Especially when showing a trend, it is often more appealing to the eye, if the lines in a chart are more 'round' A spline-chart solves this issue.
Currently it is only possible to smooth graphs if you go to advanced settings and change the chart-type from 'line' to 'spline. If you add another data-series, it is added as a line and you then have to go to advanced settings and change the chart-type again.
