how to combine line graph and bar graph using base R:
please cite following code at stackflow

par(mai = c ( 1 , 2, 1, 1), omi = c(0, 0, 0, 0))
yy <- c(31,31,31,50,50,61,69,75,80,88,94,101,108,115,121,124,125,125,125,126,127)
name1 <- c ("15","16","17","18","19","20","21","22","23","24","25","26","27","28","29","30","31","32","33","34","35")

#draw bar plot
xx <- barplot(yy, ylab = "", names.arg = name1, ylim = c(0, 140),col="steelblue")
text(xx, yy + 3, labels = as.character(yy),srt=45)
mtext(2,text="",line=2)

xx2 <- xx #c(15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35)
yy2 <-   c(379,474,579,725,922,1181,1473,1846,2316,2962,3688,4786,6069,7605,9504,10680,11074,11074,11074,11483,11484)

#transform data
yy2tx <- yy2/14000 * max(pretty(yy))

#draw line data
lines(xx2, yy2tx, lwd = 2,col="red",lty=1)
points(xx2, yy2tx, pch = 18, cex = 1,col="red")
text(xx2, yy2tx, labels = as.character(yy2),srt=90)

#draw axis for transformed data
par(mai = c ( 1 , 1, 1, 1))
axis(4, at=pretty(c(0,14000))/14000*max(pretty(yy)), labels=pretty(c(0,14000)))
grid()