\documentclass[border=0mm]{standalone}

\usepackage{cmap}
\usepackage[cp1250]{inputenc}	
\usepackage[T1]{fontenc}
\usepackage{graphicx}
\usepackage{lmodern}
\usepackage{tikz}
\usepackage{float}
\usepackage{siunitx}
\usepackage{amsmath}
\usepackage{upgreek}
\usepackage{pgfplots}
\pgfplotsset{compat=1.17}
\usepgfplotslibrary{fillbetween}
\usepgfplotslibrary{units}
% \makeatletter
%\pgfplotsset{
%  unit code/.code 2 args=
%    \begingroup
%    \protected@edef\x{\endgroup\si{#2}}\x
%} 
%\makeatother

\pgfkeys{%
  /tikz/on layer/.code={
    \pgfonlayer{#1}\begingroup
    \aftergroup\endpgfonlayer
    \aftergroup\endgroup
  }
}

\begin{document}
	\begin{tikzpicture}
		\begin{axis}[
			height=7cm,	width=11cm,	grid=major,
    		x unit=, y unit=\SI{}{\pico\second},
			xlabel=CCDLU stage no.,	ylabel=$t_\mathrm{d}$,
			ymin=48.5,ymax=53.5,
			xmin=1, xmax=16,			
			ytick distance = 1,
			xtick distance = 1,
			set layers,
			y tick label style={/pgf/number format/.cd, set thousands separator={}},
			xticklabel shift = 2 pt,
			legend pos=north west
		]					
			
			\addplot +[solid, thick,color=blue,mark=x] table [x expr=\thisrow{stage}, y expr=\thisrow{no_dummies}, col sep=semicolon] {../cadence_data/ilro_dummy_distr.csv};
			\addlegendentry{no dummies};
			\addplot +[name path = FF, solid, thick,color=red,mark=x] table [x expr=\thisrow{stage}, y expr=\thisrow{dummies}, col sep=semicolon] {../cadence_data/ilro_dummy_distr.csv};
			\addlegendentry{dummy switches};
			
		\end{axis}
	\end{tikzpicture}
\end{document}