I want to construct a normal distribution probability plot. The x-axis is for the x-values of my bins, and the y axis shows the cumulative probability on the tick labels, but the y-values are the corresponding normal distribution z-values. The format that my professor uses is: major grid with labels for the y-values seen on my plot, and a minor grid with no labels, for y-values of 2 to 9 and 91 to 98 (the commented out line in the code).
The label-less minor grid is implemented using extra y ticks. However, when I add a y-value as an extra y tick, two minor grid lines appear. Why do they appear and how do I get rid of them?
\documentclass[12pt,table]{report} \usepackage{tikz,pgfplots} \begin{document} \begin{tikzpicture}[font=\tiny,scale=1.6] \begin{axis}[ xtick pos=left, xtick={3.68,3.84,4.00,4.16,4.32,4.48,4.64,4.80,4.96,5.12}, xticklabels={3.68,3.84,4.00,4.16,4.32,4.48,4.64,4.80,4.96,5.12}, xticklabel style={shift={(0,0 |- {axis description cs:0,-0.97})}}, ytick={-2.33,-1.28,-0.84,-0.52,-0.25,0.01,0.25,0.52,0.84,1.28,2.33}, yticklabels={1.0,10.0,20.0,30.0,40.0,50.0,60.0,70.0,80.0,90.0,99.0}, % extra y ticks={-2.05,-1.88,-1.75,-1.64,-1.55,-1.48,-1.41, -1.34,1.34,1.41,1.55,1.64,1.75,1.88,2.05}, % All the extra ticks that I want extra y ticks={-2.05,-1.88,-1.75}, % best shows issue extra y tick style={tick style={draw=none},grid=minor}, minor grid style={line width=.2pt,draw=red!120}, extra y tick labels={}, major grid style={line width=.2pt,draw=gray!120}, grid=both, x axis line style={draw=none}, axis x line=middle, axis y line=middle, xmin=3.6, xmax=5.27, ymin=-2.5, ymax=2.5, domain=3.599:5.2, ] \end{axis} \end{tikzpicture} \end{document} 
