Draw Bar Graph for GNUPLOT

For example, I have a file called data.txt. And the content is:

Iker_Casillas 181
Raphael_Varane 182
Sergio_Ramos 182

May I know how to write a script for gnuplot, so I can have a bar graph as the column 1 will be the x and column 2 will be the y? And I hope that the x value can be seen clearly. Thank you

So, far here is my code

set boxwidth 1
set style data histogram
set title "Height"
set datafile separator " "
plot 'data.txt' using 2:xticlabels(1) notitle
set terminal jpeg
set output "data"
replot

But the final outcome, the x value will overlapped with each other because x value has a long name.