gnuplot: How to plot each line of a data file as Y and incremental X

Question

I have a data file containing 30 columns and N rows. Each rows correspond to 30 values of function f(x) for x={1,...,30}. The data file has following pattern:

Answer 1

UPDATED based on @Christoph's comment:

plot for [i=2:30] 'data.dat' using (i-1):(column(i)) with linespoint