The data is league-wide; note that the American League data does not start until the creation of the American League in 1901.
Historical Major League Baseball data is freely available from many sources online. This data was taken from Baseball-Reference.com[1][2]
The file was created in Gnuplot with the following code:
set terminal svg enhanced size 640 480 fname "Helvetica" fsize 12
set output "MLB_runspergame_history.svg"
set style line 1 linetype 1 pointtype 6 linewidth 2 linecolor 6 pointsize 2
set style line 2 linetype 1 pointtype 6 linewidth 2 linecolor 7 pointsize 2
set xrange [1890:2008]
set ytics 0,1,8
set yrange [3:8]
set format y "%1.0f"
set xlabel "Year"
set ylabel "Runs per game"
unset key
set boxwidth 1.0 relative
set style fill solid 1.0
plot \
"[datafile1] w filledcurves x1 linestyle 1,\
"[datafile2]" w filledcurves x1 linestyle 2
{{Information |Description={{en|1=Historical runs scored per game (by both teams) in Major League Baseball.}} |Source=Own work by uploader |Author=Grabsomepine |Date=June 1, 2008 |Permission= |other_versions= }} Average of both Ameri