I was curious, so I make some research in wikipedia.
In 1594 population was a little above 8 millions and even in 1900 population in Spain was bellow 20 millions habitants.

So number is absolutely cr*p - maybe rest of the article too...

From wikipedia:
http://es.wikipedia.org/wiki/Demograf%C3%ADa_de_Espa%C3%B1a#cite_note-15
http://es.wikipedia.org/wiki/Evoluci%C3%B3n_demogr%C3%A1fica_moderna_de_...

Evolución de la población española[16]

Año Población
1594 8.206.791
1769 9.159.999
1787 10.268.150
1797 10.541.221
1833 12.286.941
1846 12.162.872
1857 15.464.340
1877 16.622.175
1887 17.549.608
1900 18.616.630
1910 19.990.669
1920 21.388.551
1930 23.677.095
1940 26.014.278
1950 28.117.873
1960 30.582.936
1970 33.956.047
1981 37.742.561
1991 39.433.942
2001 40.499.791
2006 44.708.964
2007 45.200.737

War looking for peace,
is like fornication looking for virginity.