During which time period did Nastia Liukin compete as a gymnast?
SELECT ?value1 ?value2 WHERE { wd:Q230164 p:P641 ?s . ?s ps:P641 wd:Q3122646 . ?s pq:P2031 ?value1 . ?s pq:P2032 ?value2 }
nastia liukin: Q230164 female artistic gymnastics: Q3122646