\documentclass[border=1mm]{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{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=\SI{}{\percent}, y unit=\SI{}{\percent},
			xlabel=Injection clock duty cycle,	ylabel=${\delta}f_\mathrm{LR}$,
			ymin=2,ymax=5,
			xmin=30, xmax=70,
			ytick distance = 0.5,
			set layers,
			%x tick label style={/pgf/number format/.cd, set thousands separator={}},
			xticklabel shift = 2 pt,
			legend pos=north west,
			%xtick =\empty
		]					
			
			\addplot +[smooth, solid, thick,color=blue,mark=star] table [x=DC, y=lock range rel, col sep=semicolon] {duty_16_100.csv};
		\end{axis}
	\end{tikzpicture}
\end{document}