Data Research
by Leniolabs_
Evolution of pole materials
Sources: Materials and technology in sport. Mike Caine, Kim Blair and Mike Vasquez. NATURE MATERIALS | VOL 11 | AUGUST 2012 and Evolution of the Pole Vault Olympic Record! | Top Moments
Top countries with olympic medals
1948: Germany and Japan were not invited to participate in the games. Source link.
1980: USA and Japan were part of the boycott to protest against the Soviet invasion of Afghanistan. Source link.
1984: Russia and Poland were part of the boycott claiming 'chauvinistic sentiments and an anti-Soviet hysteria being whipped up in the United States. Source link.
Sources: Summer_Olympics_medal_table at Wikipedia.