Sparkline Column question

[jp16]

Hi, I have a set of data. Lets say 5000, 6000, 7000, 8000, 9000 and 10000. I use the Sparkline Column and select the range. HOwever, the column aint really to scale. I duno y. By right, 5000 column should be 50% the height of 10000 column but this is not the case, i discover that the lowest value in the range always has a very very low height, almost close to zero. This make the overall presentation very inaccurate.

Anyone can help?