Smooth line on histograms in gnuplot

I want to make a smooth line over histograms. So far I have tried all the smooth functions but I am not able to get the result.

For the histograms I am using:

plot "file.scatter" u (hist($2,width)):(1.0) smooth freq w boxes notitle

and the result is:

But when I ask gnuplot to draw a smooth line over these:

plot "file.scatter" u (hist($2,width)):(1.0) smooth freq w l notitle

I get:

I want the line plot to look smooth like a probability density function(of course the values will have to be normalized).

Any clues experts?