The Simplest Way to Produce the Standard Normal Distribution with Shading and Key Information Displayed

I would like to replicate

I have spent some time searching this site to find LaTeX code for producing a normal distribution that I can modify. But many use

pgfmathdeclarefunction{gauss}{2}{%
      pgfmathparse{1/(#2*sqrt(2*pi))*exp(-((x-#1)^2)/(2*#2^2))}%
    }

which produces a Gaussian curve that seems to quickly tail off to the horizontal axis and remain there, such as

which, I have not been able to alter in any way to produce thickness at the tails to suggest an asymptote. (The above is a modification of a John Canning plot as alluded to in Drawing a Normal Distribution Graph)

documentclass{article}
usepackage{pgfplots}
usepackage{amssymb, amsmath}
usepackage{tikz}
usepackage{xcolor}
pgfplotsset{compat=1.7}


begin{document}
pgfmathdeclarefunction{gauss}{2}{pgfmathparse{1/(#2*sqrt(2*pi))*exp(-((x-#1)^2)/(2*#2^2))}%
}

begin{tikzpicture}
    begin{axis}[
        no markers, domain=0:14, samples=100,
        axis lines*=left, xlabel=Standard deviations, ylabel=Frequency,,
        height=6cm, width=14cm,
        xtick={-4, -3, -2, -1, 0, 1, 2, 3, 4}, ytick=empty,
        enlargelimits=false, clip=false, axis on top,
        grid = major
    ]
        addplot [fill=cyan!20, draw=none, domain=-3:3] {gauss(0,1)} closedcycle;
        addplot [fill=orange!20, draw=none, domain=-3:-2] {gauss(0,1)} closedcycle;
        addplot [fill=orange!20, draw=none, domain=2:3] {gauss(0,1)} closedcycle;
        addplot [fill=blue!20, draw=none, domain=-2:-1] {gauss(0,1)} closedcycle;
        addplot [fill=blue!20, draw=none, domain=1:2] {gauss(0,1)} closedcycle;
        addplot[] coordinates {(-1,0.4) (1,0.4)};
        addplot[] coordinates {(-2,0.3) (2,0.3)};
        addplot[] coordinates {(-3,0.2) (3,0.2)};
        addplot[] coordinates {(-4,0) (4,0)};
        node[coordinate, pin={68.2%}] at (axis cs: 0, 0.4){};
        node[coordinate, pin={95%}] at (axis cs: 0, 0.3){};
        node[coordinate, pin={99.7%}] at (axis cs: 0, 0.2){};
        node[coordinate, pin={34.1%}] at (axis cs: -0.5, 0){};
        node[coordinate, pin={34.1%}] at (axis cs: 0.5, 0){};
        node[coordinate, pin={13.6%}] at (axis cs: 1.5, 0){};
        node[coordinate, pin={13.6%}] at (axis cs: -1.5, 0){};
        node[coordinate, pin={2.1%}] at (axis cs: 2.5, 0){};
        node[coordinate, pin={2.1%}] at (axis cs: -2.5, 0){};
    end{axis}
end{tikzpicture}
end{document}

Is there a relatively straight-forward way to mimic the first (orange) plot that is not too complicated in order to facilitate future modifications by a non-expert such as myself?

Thank you.