We need a reproducible example (reprex)
Any particular reason for using matplot?
When I try this
x = (2004:2019)
y = integer(19)
y = as.double(y)
y=y[04:19]
matplot(x, y, type="b", lty=4, pch = 18, col="blue",xlab="Year",
ylab="Total Emission",main = "Building Sector 2004-2019", lwd = '3')
all I get is a flat line with y == 0