Interpretation of the data through scatter plot
It is forming a triangle because you always have Cancelled items &lt; Total items which is expected.
Using this representation of the data is not so informative as many points are clustered and we can't assess the distribution. You might want to consider a plot such as a 2D histogram of (x=Total items, y=Proportion of Cancelled Items) in order to assess if some relation exists. And if you do so you might want to normalize each X slice so as to visualize the distribution for each range [Xmin, Xmax]
If you are looking for a linear regression, you might want to use scikit-learn to fit a linearRegression model with X = total Items and Y=Cancelled Items and check the correlation coefficient.