plot(data[,1],data[,13],
    type="l",
    log="x",
    xlab="Redshift [n.u.]",
    ylab="n/nₜₒₜ [n.u.]",
    xaxp=c(1,5,1),lty=3)
lines(data[,1],data[,11],
    type="l",
    lty=2)
legend( x="left", 
        legend=c("H⁺/H","H⁰/H"),
        col=c("black","black"), lwd=1, lty=c(3,2), merge=FALSE )