Making one line graph with two different time interval data from 2 plot

Dear All,
Good day. Hope you are fine. I was trying to create one line graph where two plot data can be shown. Note that one plot has tree diameter data from 1949 to 2014 with unequal census interval and the other plot has data from 1977 to 2014. I have attached an example of graph where you can see some lines starts from 2008 and some from 2012. I tried a lot but could not do it.
Also I want the x-axis year interval 10 years. For example, 1950, 1960, 1970….From format axis option I tried to set the interval unit 10 but it doesn’t work.
I am attaching you the data and sample graph. Can you please help me. It would be really a great help. Please not that I am using office2010.

Thanks
Kind Regards
Sohel

I am not seeing where you have data starting on 2008 or 2014. Also I'm not sure what your issue is with the display itself. The lines should start and stop on the dates indicated.

As for the X-axis, you are trying to plot 1948, 1949, etc. These aren't years, they are numbers which can be interpreted as the dates 5/1/1905 and 5/2/1905. If you want to plot them properly, you need to convert them to years. For example =date(A2,1,1). Will convert 1948 to January 1, 1948. Then display it with "yyyy" format.

Then format the axis and select date as the type. Then set the min date to 1/1/1940 (Since you want to capture 1948 and 1949) and the max date to 1/1/2020. Then you can set the major unit to 10. You may have to set the axis to format "yyyy."