Table: village_slovene_stats_4
Columns: village_german
village_slovene
number_of_people_1991
percent_of_slovenes_1991
percent_of_slovenes_1951

Question: How many people in 1991 have a Village (German) of rupertiberg?
SQL: SELECT COUNT("number_of_people_1991") FROM village_slovene_stats_4 WHERE "village_german" = 'rupertiberg'