It seems that, on average, a third (actually 31%) of a crash occurs before the maximum decline and 2/3rds (actually 69%) occurs afterwards, however, the location of the maximum decline looks pretty random.
==Other sources for the Op Ed==
*Forbes: https://www.forbes.com/sites/sergeiklebnikov/2020/07/23/historical-stock-market-returns-under-every-us-president/#e5c3268faaf4
*WSJ: https://www.wsj.com/articles/stock-scenarios-for-a-madcap-year-11597607961
*Business insider: https://www.businessinsider.com/stock-market-coronavirus-crash-not-over-how-to-invest-bofa-2020-3
==Building the Paper==
The St. Louis Fed has data on Aaa and Baa Corporate Bonds:
*https://fred.stlouisfed.org/series/AAA
*https://fred.stlouisfed.org/series/BAA