Uneven dates as x-axis labels and scale

I have a time serie which I want to display on a line chart. For several years, I have monthly data. Data for the next 5 years is forecast, but on an annual basis. In excel, I show the historical monthly data on the graph and, at the end of the line, I add the annual forecast data for 5 years. I then make the scale of the x axis annual so that labels only show years. I declare the major unites as years and the minor units as months. That allows me to show the annual data correctly spaced out on the graph, together with the monthly data.

I don't seem to be able to do this in xcelsius. Can I have your advice please?