My first suggestion is a scatter plot.
If 10000 dots unevenly spread in your plot is still a vague cloud, consider a heat map. The colour of the pixel at x = 10.5, y = 11.5 would indicate how many times value between 10.45 and 10.55 is mapped onto a value between 11.45 and 11.55 : 0 = white = RGB(255,255,255), 1 = blue = RGB(0,0,255), 2 = RGB(1,0,254), ... 256 and above = RGB(255,0,0) = red
