X axis - week ending - narrow the number of points displayed?

[#1]

I have a chart that displays a rolling 2 year group of activity. The X axis is currently showing every week ending and it looks cramped.  When I make the chart smaller it then shows only the first however many weeks.  I would like it to show the min and max week and then every 2 or 3 weeks inbetween.  Can anyone give me any ideas?

When I select continuous in the dimension axis to set a static Min and static Max it then changes the dates to numbers?

I need to be able to do this so that in a printable report the axis is legible

Thank you

[Gysbert_Wassenaar]

You can change the Number format of the continuous axis on the Numbers tab. You can set it to a date format for example. Choose the Date option and enter a date format string like  DD/MM/YYYY

[#3]

Thank you this works for the numbers to dates but now it expresses the dates at the 1st of the month. 1/5/2015, 1/07/2015 etc

What I would like to show is something like 1/3/2015,15/3/2015, 5/04/2015 etc every fortnight? Any ideas

Thanks again