Very interesting. I think a line graph would have been a better choice than the stacked line graph -- the undulations in the bottom layers make it hard to see the phenomenon being discussed, which is the flatness of the Philippines.
I'm sampling a few points from the chart and will try to create the corresponding line graph.
I have seen programs to help with this digitization of graphs. At times some data sets (the graphs) have no other raw data shown or available, so the only way to do further analysis is to reverse engineer the only data set you are given. Low tech is awesome.