Hello, I am trying to make a line graph with 25 lines, one for each department, but I keep getting 25 graphs with one line each. I want to find a way to make the one line graph or a way to overlay or overlap the 25 graphs. thank you in advance

forvalues i = 1(1)25 {
local lines line g_math año if departamento==`i'

#delimit ;
twoway
(`lines'),
xlabel(2008[1]2016)
legend(off)
ti("Evolución de puntajes")
subti("Promedio a nivel departamento-año")
yti("Puntaje en matemática (año base 2014)")
xti("Año")
xsize(7)
ysize(10);
#delimit cr

graph save graf`i' , replace

}