Calculate x-coord from given y-coord in data table

Question

I am trying to plot a couple of chi-squared cdfs and I'd like to draw a vertical line intersecting with then it hits a certain value, e.g. 0.005.

Given I know the y value how can I find the intersecting x value?

\documentclass{article}
\usepackage{pgfplots}
\pgfplotsset{width=10cm,compat=newest}
\begin{filecontents}{data.csv}
0,0,0
0.05005,0.17702,0.00037825
0.1001,0.24829,0.00058426
0.15015,0.30161,0.00077812
0.2002,0.34544,0.00097319
0.25025,0.3831,0.0011743
0.3003,0.41631,0.001384
0.35035,0.44609,0.0016036
0.4004,0.47312,0.0018341
0.45045,0.49788,0.0020762
0.5005,0.52072,0.0023304
0.55055,0.54191,0.0025973
0.6006,0.56165,0.0028771
0.65065,0.58012,0.0031702
0.7007,0.59745,0.003477
0.75075,0.61376,0.0037977
0.8008,0.62915,0.0041325
0.85085,0.64369,0.0044819
0.9009,0.65746,0.0048459
0.95095,0.67052,0.0052249
1.001,0.68293,0.005619
\end{filecontents}
\begin{document}
\begin{figure}
\centering

\begin{tikzpicture}
    \begin{axis}[
        xmin=0, xmax=50,
        ymin=0, ymax=1,
        grid=both,
        minor tick num = 1,
        major grid style = {lightgray},
        minor grid style = {lightgray!25},
        width=0.75\linewidth,
        xlabel={$x$},   ylabel={$\text{cdf}(x)$},
        legend pos=south east,]
    \pgfplotstableread[col sep=comma]{data.csv}\data

    \addplot[smooth, very thick, blue]  table[x index = {0}, y index = {1}] {\data};
    \addplot[smooth, very thick, red]   table[x index = {0}, y index = {2}] {\data};

    \legend{$\mathcal{H}_{0}$, $\mathcal{H}_{1}$};
\end{axis}

\end{tikzpicture}
\end{figure}
\end{document}