Presumably 'wiggle' in the 2010 column is from Jason Derulo's song which repeats that word over and over! And 'diamond' must be from Rihanna's song. 'burn' from Ellie Goulding...hmm it seems like a decent chunk of the words come from being repeated in a chorus. Cool analysis though, enjoyed reading.
there are a few songs that use wiggle, most LMFAO songs for example
1965-2015 is 51 years, not 50. More importantly, cutting off your survey at 1965 shortchanges the Beatles (who had nine year-end top 100 hits in 1964) and creates a misleading result.