For the 5 years 2014-2018 the @ES/@RTY (S&P500/Russel2000) ratio traded in the range 1.53/1.89.
In 2019 this ratio widened most of the year from 1.85 to 1.938
In the first 9 weeks of 2020 this widened further to 2.00
In the last 10 days it has exploded to 2.16 which in terms of a move is almost 50% of the entire 5 year 2014-2018 range!