You can use multi-function charts to compare variables that are not the same scale.
With multi-function charts, you can assign a y-axis for each series or an x-axis if you want to compare data sets of different categories. Each axis can be placed to the right or left of the chart. You can swap the functions to swap the y-axis on which they are plotted from right to left.
For example, you can chart the count of events grouped by channel and level in addition to the average of tasks grouped by channel and level.