Gnuplot：标题中的空间和直方图中的xtics（条形图）

Gnuplot 4.6.5

我想在Gnuplot制作的条形图（直方图）的x轴的标题和tic中留一些空间。

演示在这里：

脚本：https : //dl.dropboxusercontent.com/u/45318932/histograms.2.plt数据文件：https : //dl.dropboxusercontent.com/u/45318932/immigration.dat

该脚本来自Gnuplot演示网站，未经修改：

# set terminal pngcairo  transparent enhanced font "arial,10" fontscale 1.0 size 500, 350 
# set output 'histograms.2.png'
set boxwidth 0.9 absolute
set style fill   solid 1.00 border lt -1
set key inside right top vertical Right noreverse noenhanced autotitles nobox
set style histogram clustered gap 1 title  offset character 0, 0, 0
set datafile missing '-'
set style data histograms
set xtics border in scale 0,0 nomirror rotate by -45  offset character 0, 0, 0 autojustify
set xtics  norangelimit font ",8"
set xtics   ()
set title "US immigration from Northern Europe\nPlot selected data columns as histogram of clustered boxes" 
set yrange [ 0.00000 : 300000. ] noreverse nowriteback
i = 22
plot 'immigration.dat' using 6:xtic(1) ti col, '' u 12 ti col, '' u 13 ti col, '' u 14 ti col

我略微更改了数据，目的是在标题和X标记中留出一些空间（请参见“丹麦国家”和“ 1891-1900”）：

# IMMIGRATION BY REGION AND SELECTED COUNTRY OF LAST RESIDENCE
#
Region  Austria Hungary Belgium Czechoslovakia  'Denmark country'   France  Germany Greece  Ireland Italy   Netherlands Norway  Sweden  Poland  Portugal    Romania Soviet_Union    Spain   Switzerland United_Kingdom  Yugoslavia  Other_Europe    TOTAL   
'1891 - 1900'   234081  181288  18167   -   50231   30770   505152  15979   388416  651893  26758   95015   226266  96720   27508   12750   505290  8731    31179   271538  -   282 3378014 
1901-1910   668209  808511  41635   -   65285   73379   341498  167519  339065  2045877 48262   190505  249534  -   69149   53008   1597306 27935   34922   525950  -   39945   7387494 
1911-1920   453649  442693  33746   3426    41983   61897   143945  184201  146181  1109524 43718   66395   95074   4813    89732   13311   921201  68611   23091   341408  1888    31400   4321887 
1921-1930   32868   30680   15846   102194  32430   49610   412202  51084   211234  455315  26948   68531   97249   227734  29994   67646   61742   28958   29676   339570  49064   42619   2463194 
1931-1940   3563    7861    4817    14393   2559    12623   144058  9119    10973   68028   7150    4740    3960    17026   3329    3871    1370    3258    5512    31572   5835    11949   377566  
1941-1950   24860   3469    12189   8347    5393    38809   226578  8973    19789   57661   14860   10100   10665   7571    7423    1076    571 2898    10547   139306  1576    8486    621147  
1951-1960   67106   36637   18575   918 10984   51121   477765  47608   43362   185491  52277   22935   21697   9985    19588   1039    671 7894    17675   202824  8225    16350   1325727 
1961-1970   20621   5401    9192    3273    9201    45237   190796  85969   32966   214111  30606   15484   17116   53539   76065   3531    2465    44659   18453   213822  20381   11604   1124492 

但是，输出是这样的：

我添加的空间未显示。

无论如何，我可以得到图中想要的空间吗？