Consider the numbers of community hospital beds per 1000 population
that are available in each state in the U.S. and in the District of
Columbia.  The datasets "bed.dat" contains these values for both
1980 and 1986.  The variables are:

    bed80 -- 1980 value of beds per 1000 population
    bed86 -- 1986 value of beds per 1000 population
    state -- numeric code for state