I need to make a very intricate graph. What's a good program to use?

I need to have an x axis of 70 steps and a y axis of a 200–300, with 4 lines of connected dots (occasionally up to 6) in the graph itself. Hopefully different colors. I thought this would be no problem using Excel or Numbers (the Mac equivalent to Excel), but it seems limited to a certain number of steps (ah! really?), and overall cumbersome to use with so many points to enter. What’s a good, FAST-to-use program to create this kind of thing? Thanks!