I remember in the 1970s when the Soviet Union was called a gerontocracy. Gorbachev becoming general Secretary at the age of 54 was seen as a breath of fresh air. As your chart shows, one third of the US Senate is over the age of 70. We have people like Biden and Trump as president. Sign of the times (who are respectively 10 and 7 years older than Xi). Incidentally, Xi is the oldest member of the Politburo Standing Committee.